Render should always return a html template (#4612)

cast/src/launcher/layout/hc-cast.ts

@@ -39,7 +39,7 @@ class HcCast extends LitElement {
   @property() private askWrite = false;
   @property() private lovelaceConfig?: LovelaceConfig | null;
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     if (this.lovelaceConfig === undefined) {
       return html`
         <loading-screen></loading-screen>>

cast/src/launcher/layout/hc-connect.ts

@@ -70,7 +70,7 @@ export class HcConnect extends LitElement {
   @property() private castManager?: CastManager | null;
   private openDemo = false;
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     if (this.cannotConnect) {
       const tokens = loadTokens();
       return html`

cast/src/launcher/layout/hc-layout.ts

@@ -22,7 +22,7 @@ class HcLayout extends LitElement {
   @property() public connection?: Connection;
   @property() public user?: HassUser;
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     return html`
       <ha-card>
         <div class="layout">

cast/src/receiver/layout/hc-demo.ts

@@ -16,7 +16,7 @@ class HcDemo extends HassElement {
   @property() public lovelacePath!: string;
   @property() private _lovelaceConfig?: LovelaceConfig;
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     if (!this._lovelaceConfig) {
       return html``;
     }

cast/src/receiver/layout/hc-launch-screen.ts

@@ -14,7 +14,7 @@ class HcLaunchScreen extends LitElement {
   @property() public hass?: HomeAssistant;
   @property() public error?: string;
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     return html`
       <div class="container">
         <img

cast/src/receiver/layout/hc-lovelace.ts

@@ -22,7 +22,7 @@ class HcLovelace extends LitElement {
 
   @property() public viewPath?: string | number;
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     const index = this._viewIndex;
     if (index === undefined) {
       return html`

cast/src/receiver/layout/hc-main.ts

@@ -50,7 +50,7 @@ export class HcMain extends HassElement {
     }
   }
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     if (this._showDemo) {
       return html`
         <hc-demo .lovelacePath=${this._lovelacePath}></hc-demo>

demo/src/custom-cards/cast-demo-row.ts

@@ -27,7 +27,7 @@ class CastDemoRow extends LitElement implements LovelaceRow {
     // No config possible.
   }
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     if (
       !this._castManager ||
       this._castManager.castState === "NO_DEVICES_AVAILABLE"

gallery/src/demos/demo-util-long-press.ts

@@ -6,7 +6,7 @@ import { actionHandler } from "../../../src/panels/lovelace/common/directives/ac
 import { ActionHandlerEvent } from "../../../src/data/lovelace";
 
 export class DemoUtilLongPress extends LitElement {
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     return html`
       ${this.renderStyle()}
       ${[1, 2, 3].map(

hassio/src/addon-store/hassio-addon-repository.ts

@@ -36,7 +36,7 @@ class HassioAddonRepositoryEl extends LitElement {
     }
   );
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     const repo = this.repo;
     const addons = this._getAddons(this.addons, this.filter);
 

hassio/src/addon-store/hassio-addon-store.ts

@@ -48,7 +48,7 @@ class HassioAddonStore extends LitElement {
     await this._loadData();
   }
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     if (!this._addons || !this._repos) {
       return html`
         <loading-screen></loading-screen>

hassio/src/addon-store/hassio-repositories-editor.ts

@@ -33,7 +33,7 @@ class HassioRepositoriesEditor extends LitElement {
       .sort((a, b) => (a.name < b.name ? -1 : 1))
   );
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     const repos = this._sortedRepos(this.repos);
     return html`
       <div class="card-group">

hassio/src/addon-view/hassio-addon-audio.ts

@@ -39,7 +39,7 @@ class HassioAddonAudio extends LitElement {
   @property() private _selectedInput!: null | string;
   @property() private _selectedOutput!: null | string;
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     return html`
       <paper-card heading="Audio">
         <div class="card-content">

hassio/src/addon-view/hassio-addon-config.ts

@@ -31,7 +31,7 @@ class HassioAddonConfig extends LitElement {
   @property() private _config!: string;
   @property({ type: Boolean }) private _configHasChanged = false;
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     return html`
       <paper-card heading="Config">
         <div class="card-content">

hassio/src/addon-view/hassio-addon-info.ts

@@ -95,7 +95,7 @@ class HassioAddonInfo extends LitElement {
   @property() public addon!: HassioAddonDetails;
   @property() private _error?: string;
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     return html`
       ${
         this._computeUpdateAvailable

hassio/src/addon-view/hassio-addon-logs.ts

@@ -31,7 +31,7 @@ class HassioAddonLogs extends LitElement {
     await this._loadData();
   }
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     return html`
       <paper-card heading="Log">
         ${this._error

hassio/src/addon-view/hassio-addon-network.ts

@@ -44,7 +44,7 @@ class HassioAddonNetwork extends LitElement {
     this._setNetworkConfig();
   }
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     if (!this._config) {
       return html``;
     }

hassio/src/addon-view/hassio-addon-view.ts

@@ -33,7 +33,7 @@ class HassioAddonView extends LitElement {
   @property() public route!: Route;
   @property() public addon?: HassioAddonDetails;
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     if (!this.addon) {
       return html`
         <paper-spinner-lite active></paper-spinner-lite>

hassio/src/components/hassio-card-content.ts

@@ -23,7 +23,7 @@ class HassioCardContent extends LitElement {
   @property() public iconClass?: string;
   @property() public icon = "hass:help-circle";
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     return html`
       <iron-icon
         class=${this.iconClass}

hassio/src/components/hassio-search-input.ts

@@ -16,7 +16,7 @@ import "@material/mwc-button";
 class HassioSearchInput extends LitElement {
   @property() private filter?: string;
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     return html`
       <div class="search-container">
         <paper-input

hassio/src/dashboard/hassio-addons.ts

@@ -21,7 +21,7 @@ class HassioAddons extends LitElement {
   @property() public hass!: HomeAssistant;
   @property() public addons?: HassioAddonInfo[];
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     return html`
       <div class="content card-group">
         <div class="title">Add-ons</div>

hassio/src/dashboard/hassio-dashboard.ts

@@ -24,7 +24,7 @@ class HassioDashboard extends LitElement {
   @property() public hassInfo!: HassioHomeAssistantInfo;
   @property() public hassOsInfo!: HassioHassOSInfo;
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     return html`
       <div class="content">
         <hassio-update

hassio/src/dashboard/hassio-update.ts

@@ -32,7 +32,7 @@ export class HassioUpdate extends LitElement {
   @property() public supervisorInfo: HassioSupervisorInfo;
   @property() private _error?: string;
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     const updatesAvailable: number = [
       this.hassInfo,
       this.supervisorInfo,

hassio/src/dialogs/markdown/dialog-hassio-markdown.ts

@@ -32,7 +32,7 @@ class HassioMarkdownDialog extends LitElement {
     this._dialog.open();
   }
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     return html`
       <ha-paper-dialog id="dialog" with-backdrop="">
         <app-toolbar>

hassio/src/dialogs/snapshot/dialog-hassio-snapshot.ts

@@ -102,7 +102,7 @@ class HassioSnapshotDialog extends LitElement {
     }
   }
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     if (!this.snapshot) {
       return html``;
     }

hassio/src/hassio-pages-with-tabs.ts

@@ -41,7 +41,7 @@ class HassioPagesWithTabs extends LitElement {
   @property() public hassInfo!: HassioHomeAssistantInfo;
   @property() public hassOsInfo!: HassioHassOSInfo;
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     const page = this._page;
     return html`
       <app-header-layout has-scrolling-region>

hassio/src/ingress-view/hassio-ingress-view.ts

@@ -23,7 +23,7 @@ class HassioIngressView extends LitElement {
   @property() public route!: Route;
   @property() private _addon?: HassioAddonDetails;
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     if (!this._addon) {
       return html`
         <hass-loading-screen></hass-loading-screen>

hassio/src/snapshots/hassio-snapshots.ts

@@ -76,7 +76,7 @@ class HassioSnapshots extends LitElement {
     await this._updateSnapshots();
   }
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     return html`
       <div class="content">
         <div class="card-group">

src/cards/ha-badges-card.ts

@@ -12,7 +12,7 @@ class HaBadgesCard extends LitElement {
   @property() public hass?: HomeAssistant;
   @property() public states?: HassEntity[];
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     if (!this.hass || !this.states) {
       return html``;
     }

src/common/search/search-input.ts

@@ -20,7 +20,7 @@ class SearchInput extends LitElement {
     this.shadowRoot!.querySelector("paper-input")!.focus();
   }
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     return html`
       <div class="search-container">
         <paper-input

src/components/device/ha-area-devices-picker.ts

@@ -255,9 +255,9 @@ export class HaAreaDevicesPicker extends SubscribeMixin(LitElement) {
     }
   }
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     if (!this._devices || !this._areas || !this._entities) {
-      return;
+      return html``;
     }
     const areas = this._getDevices(
       this._devices,

src/components/device/ha-device-automation-picker.ts

@@ -83,7 +83,7 @@ export abstract class HaDeviceAutomationPicker<
     return `${this._automations[idx].device_id}_${idx}`;
   }
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     if (this._renderEmpty) {
       return html``;
     }

src/components/device/ha-device-picker.ts

@@ -203,9 +203,9 @@ export class HaDevicePicker extends SubscribeMixin(LitElement) {
     ];
   }
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     if (!this.devices || !this.areas || !this.entities) {
-      return;
+      return html``;
     }
     const devices = this._getDevices(
       this.devices,

src/components/device/ha-devices-picker.ts

@@ -37,9 +37,9 @@ class HaDevicesPicker extends LitElement {
   public pickedDeviceLabel?: string;
   @property({ attribute: "pick-device-label" }) public pickDeviceLabel?: string;
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     if (!this.hass) {
-      return;
+      return html``;
     }
 
     const currentDevices = this._currentDevices;

src/components/entity/ha-entities-picker.ts

@@ -40,9 +40,9 @@ class HaEntitiesPickerLight extends LitElement {
   public pickedEntityLabel?: string;
   @property({ attribute: "pick-entity-label" }) public pickEntityLabel?: string;
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     if (!this.hass) {
-      return;
+      return html``;
     }
 
     const currentEntities = this._currentEntities;

src/components/entity/ha-entity-picker.ts

@@ -145,7 +145,7 @@ class HaEntityPicker extends LitElement {
     }
   }
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     const states = this._getStates(
       this._hass,
       this.includeDomains,

src/components/entity/ha-entity-toggle.ts

@@ -28,7 +28,7 @@ class HaEntityToggle extends LitElement {
   @property() public stateObj?: HassEntity;
   @property() private _isOn: boolean = false;
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     if (!this.stateObj) {
       return html`
         <ha-switch disabled></ha-switch>

src/components/entity/ha-state-label-badge.ts

@@ -52,7 +52,7 @@ export class HaStateLabelBadge extends LitElement {
     this.clearInterval();
   }
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     const state = this.state;
 
     if (!state) {

src/components/entity/state-badge.ts

@@ -28,7 +28,7 @@ export class StateBadge extends LitElement {
   @property({ type: Boolean }) public stateColor?: boolean;
   @query("ha-icon") private _icon!: HaIcon;
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     const stateObj = this.stateObj;
 
     if (!stateObj) {

src/components/ha-area-picker.ts

@@ -85,9 +85,9 @@ export class HaAreaPicker extends SubscribeMixin(LitElement) {
     ];
   }
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     if (!this._areas) {
-      return;
+      return html``;
     }
     return html`
       <vaadin-combo-box-light

src/components/ha-attributes.ts

@@ -16,7 +16,7 @@ class HaAttributes extends LitElement {
   @property() public stateObj?: HassEntity;
   @property() public extraFilters?: string;
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     if (!this.stateObj) {
       return html``;
     }

src/components/ha-camera-stream.ts

@@ -42,7 +42,7 @@ class HaCameraStream extends LitElement {
     this._attached = false;
   }
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     if (!this.stateObj || !this._attached) {
       return html``;
     }

src/components/ha-form/ha-form-positive_time_period_dict.ts

@@ -23,7 +23,7 @@ export class HaFormTimePeriod extends LitElement implements HaFormElement {
     }
   }
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     return html`
       <paper-time-input
         .label=${this.label}

src/components/ha-label-badge.ts

@@ -17,7 +17,7 @@ class HaLabelBadge extends LitElement {
   @property() public description?: string;
   @property() public image?: string;
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     return html`
       <div class="badge-container">
         <div class="label-badge" id="badge">

src/components/ha-menu-button.ts

@@ -42,7 +42,7 @@ class HaMenuButton extends LitElement {
     }
   }
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     const hasNotifications =
       (this.narrow || this.hass.dockedSidebar === "always_hidden") &&
       (this._hasNotifications ||

src/components/ha-related-items.ts

@@ -64,7 +64,7 @@ export class HaRelatedItems extends SubscribeMixin(LitElement) {
     }
   }
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     if (!this._related) {
       return html``;
     }

src/components/map/ha-location-editor.ts

@@ -50,7 +50,7 @@ class LocationEditor extends LitElement {
     this._ignoreFitToMap = this.location;
   }
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     return html`
       <div id="map"></div>
     `;

src/components/map/ha-locations-editor.ts

@@ -90,7 +90,7 @@ export class HaLocationsEditor extends LitElement {
     }
   }
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     return html`
       <div id="map"></div>
     `;

src/components/user/ha-user-badge.ts

@@ -31,7 +31,7 @@ const computeInitials = (name: string) => {
 class StateBadge extends LitElement {
   @property() public user?: User | CurrentUser;
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     const user = this.user;
     const initials = user ? computeInitials(user.name) : "?";
     return html`

src/components/user/ha-user-picker.ts

@@ -34,7 +34,7 @@ class HaUserPicker extends LitElement {
       .sort((a, b) => compare(a.name, b.name));
   });
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     return html`
       <paper-dropdown-menu-light .label=${this.label}>
         <paper-listbox

src/dialogs/config-entry-system-options/dialog-config-entry-system-options.ts

@@ -48,7 +48,7 @@ class DialogConfigEntrySystemOptions extends LitElement {
     await this.updateComplete;
   }
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     if (!this._params) {
       return html``;
     }

src/dialogs/config-flow/dialog-data-entry-flow.ts

@@ -116,7 +116,7 @@ class DataEntryFlowDialog extends LitElement {
     this._scheduleCenterDialog();
   }
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     if (!this._params) {
       return html``;
     }

src/dialogs/config-flow/step-flow-abort.ts

@@ -24,7 +24,7 @@ class StepFlowAbort extends LitElement {
   @property()
   private step!: DataEntryFlowStepAbort;
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     return html`
       <h2>
         ${this.hass.localize(

src/dialogs/config-flow/step-flow-create-entry.ts

@@ -36,7 +36,7 @@ class StepFlowCreateEntry extends LitElement {
   @property()
   public devices!: DeviceRegistryEntry[];
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     const localize = this.hass.localize;
 
     return html`

src/dialogs/config-flow/step-flow-external.ts

@@ -28,7 +28,7 @@ class StepFlowExternal extends LitElement {
   @property()
   private step!: DataEntryFlowStepExternal;
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     const localize = this.hass.localize;
 
     return html`

src/dialogs/config-flow/step-flow-form.ts

@@ -40,7 +40,7 @@ class StepFlowForm extends LitElement {
   @property()
   private _errorMsg?: string;
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     const step = this.step;
     const stepData = this._stepDataProcessed;
 

src/dialogs/config-flow/step-flow-loading.ts

@@ -10,7 +10,7 @@ import "@polymer/paper-spinner/paper-spinner-lite";
 
 @customElement("step-flow-loading")
 class StepFlowLoading extends LitElement {
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     return html`
       <div class="init-spinner">
         <paper-spinner-lite active></paper-spinner-lite>

src/dialogs/config-flow/step-flow-pick-handler.ts

@@ -59,7 +59,7 @@ class StepFlowPickHandler extends LitElement {
     );
   });
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     const handlers = this._getHandlers(this.handlers, this.filter);
 
     return html`

src/dialogs/device-registry-detail/dialog-device-registry-detail.ts

@@ -44,7 +44,7 @@ class DialogDeviceRegistryDetail extends LitElement {
     await this.updateComplete;
   }
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     if (!this._params) {
       return html``;
     }

src/dialogs/domain-toggler/dialog-domain-toggler.ts

@@ -22,7 +22,7 @@ class DomainTogglerDialog extends LitElement {
     this._params = params;
   }
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     if (!this._params) {
       return html``;
     }

src/dialogs/generic/dialog-box.ts

@@ -32,7 +32,7 @@ class DialogBox extends LitElement {
     }
   }
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     if (!this._params) {
       return html``;
     }

src/dialogs/more-info/controls/more-info-automation.ts

@@ -19,7 +19,7 @@ class MoreInfoAutomation extends LitElement {
   @property() public hass!: HomeAssistant;
   @property() public stateObj?: HassEntity;
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     if (!this.hass || !this.stateObj) {
       return html``;
     }

src/dialogs/more-info/controls/more-info-camera.ts

@@ -38,7 +38,7 @@ class MoreInfoCamera extends LitElement {
     this._attached = false;
   }
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     if (!this._attached || !this.hass || !this.stateObj) {
       return html``;
     }

src/dialogs/more-info/controls/more-info-climate.ts

@@ -39,7 +39,7 @@ class MoreInfoClimate extends LitElement {
   @property() public stateObj?: ClimateEntity;
   private _resizeDebounce?: number;
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     if (!this.stateObj) {
       return html``;
     }

src/dialogs/more-info/controls/more-info-counter.ts

@@ -17,7 +17,7 @@ class MoreInfoCounter extends LitElement {
   @property() public hass!: HomeAssistant;
   @property() public stateObj?: HassEntity;
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     if (!this.hass || !this.stateObj) {
       return html``;
     }

src/dialogs/more-info/controls/more-info-default.ts

@@ -16,7 +16,7 @@ class MoreInfoDefault extends LitElement {
   @property() public hass!: HomeAssistant;
   @property() public stateObj?: HassEntity;
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     if (!this.hass || !this.stateObj) {
       return html``;
     }

src/dialogs/more-info/controls/more-info-script.ts

@@ -16,7 +16,7 @@ class MoreInfoScript extends LitElement {
   @property() public hass!: HomeAssistant;
   @property() public stateObj?: HassEntity;
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     if (!this.hass || !this.stateObj) {
       return html``;
     }

src/dialogs/more-info/controls/more-info-sun.ts

@@ -19,7 +19,7 @@ class MoreInfoSun extends LitElement {
   @property() public hass!: HomeAssistant;
   @property() public stateObj?: HassEntity;
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     if (!this.hass || !this.stateObj) {
       return html``;
     }

src/dialogs/more-info/controls/more-info-timer.ts

@@ -19,7 +19,7 @@ class MoreInfoTimer extends LitElement {
 
   @property() public stateObj?: TimerEntity;
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     if (!this.hass || !this.stateObj) {
       return html``;
     }

src/dialogs/more-info/controls/more-info-weather.ts

@@ -72,7 +72,7 @@ class MoreInfoWeather extends LitElement {
     return false;
   }
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     if (!this.hass || !this.stateObj) {
       return html``;
     }

src/dialogs/notifications/configurator-notification-item.ts

@@ -19,7 +19,7 @@ export class HuiConfiguratorNotificationItem extends LitElement {
 
   @property() public notification?: PersitentNotificationEntity;
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     if (!this.hass || !this.notification) {
       return html``;
     }

src/dialogs/notifications/notification-item-template.ts

@@ -11,7 +11,7 @@ import "../../components/ha-card";
 
 @customElement("notification-item-template")
 export class HuiNotificationItemTemplate extends LitElement {
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     return html`
       <ha-card>
         <div class="header"><slot name="header"></slot></div>

src/dialogs/notifications/notification-item.ts

@@ -28,7 +28,7 @@ export class HuiNotificationItem extends LitElement {
     return false;
   }
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     if (!this.hass || !this.notification) {
       return html``;
     }

src/dialogs/notifications/persistent-notification-item.ts

@@ -23,7 +23,7 @@ export class HuiPersistentNotificationItem extends LitElement {
 
   @property() public notification?: PersistentNotification;
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     if (!this.hass || !this.notification) {
       return html``;
     }

src/dialogs/zha-device-info-dialog/dialog-zha-device-info.ts

@@ -34,7 +34,7 @@ class DialogZHADeviceInfo extends LitElement {
     this._dialog.open();
   }
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     if (!this._params || !this._device) {
       return html``;
     }

src/layouts/hass-error-screen.ts

@@ -15,7 +15,7 @@ class HassErrorScreen extends LitElement {
   @property()
   public error?: string;
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     return html`
       <hass-subpage>
         <div class="content">

src/layouts/hass-loading-screen.ts

@@ -20,7 +20,7 @@ class HassLoadingScreen extends LitElement {
   @property() public hass?: HomeAssistant;
   @property() public narrow?: boolean;
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     return html`
       <app-toolbar>
         ${this.rootnav

src/layouts/hass-subpage.ts

@@ -20,7 +20,7 @@ class HassSubpage extends LitElement {
   @property({ type: Boolean })
   public hassio = false;
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     return html`
       <div class="toolbar">
         <ha-paper-icon-button-arrow-prev

src/layouts/home-assistant-main.ts

@@ -38,11 +38,11 @@ class HomeAssistantMain extends LitElement {
   @property() public route?: Route;
   @property({ type: Boolean }) private narrow?: boolean;
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     const hass = this.hass;
 
     if (!hass) {
-      return;
+      return html``;
     }
 
     const sidebarNarrow = this._sidebarNarrow;

src/layouts/loading-screen.ts

@@ -10,7 +10,7 @@ import {
 
 @customElement("loading-screen")
 class LoadingScreen extends LitElement {
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     return html`
       <paper-spinner-lite active></paper-spinner-lite>
     `;

src/managers/notification-manager.ts

@@ -58,7 +58,7 @@ class NotificationManager extends LitElement {
     });
   }
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     return html`
       <ha-toast .noCancelOnOutsideClick=${this._noCancelOnOutsideClick}>
         ${this._action

src/onboarding/ha-onboarding.ts

@@ -50,7 +50,7 @@ class HaOnboarding extends litLocalizeLiteMixin(HassElement) {
   @property() private _loading = false;
   @property() private _steps?: OnboardingStep[];
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     const step = this._curStep()!;
 
     if (this._loading || !step) {
@@ -79,6 +79,7 @@ class HaOnboarding extends litLocalizeLiteMixin(HassElement) {
         ></onboarding-integrations>
       `;
     }
+    return html``;
   }
 
   protected firstUpdated(changedProps: PropertyValues) {

src/onboarding/integration-badge.ts

@@ -16,7 +16,7 @@ class IntegrationBadge extends LitElement {
   @property() public badgeIcon?: string;
   @property({ type: Boolean, reflect: true }) public clickable = false;
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     return html`
       <div class="icon">
         <iron-icon .icon=${this.icon}></iron-icon>

src/onboarding/onboarding-core-config.ts

@@ -41,7 +41,7 @@ class OnboardingCoreConfig extends LitElement {
   @property() private _unitSystem!: ConfigUpdateValues["unit_system"];
   @property() private _timeZone!: string;
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     return html`
       <p>
         ${this.onboardingLocalize(

src/onboarding/onboarding-create-user.ts

@@ -28,7 +28,7 @@ class OnboardingCreateUser extends LitElement {
   @property() private _loading = false;
   @property() private _errorMsg?: string = undefined;
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     return html`
     <p>
       ${this.localize("ui.panel.page-onboarding.intro")}

src/onboarding/onboarding-integrations.ts

@@ -51,7 +51,7 @@ class OnboardingIntegrations extends LitElement {
     }
   }
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     if (!this._entries || !this._discovered) {
       return html``;
     }

src/onboarding/onboarding-loading.ts

@@ -9,7 +9,7 @@ import {
 
 @customElement("onboarding-loading")
 class OnboardingLoading extends LitElement {
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     return html`
       <div class="loader"></div>
     `;

src/panels/config/areas/dialog-area-registry-detail.ts

@@ -32,7 +32,7 @@ class DialogAreaDetail extends LitElement {
     await this.updateComplete;
   }
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     if (!this._params) {
       return html``;
     }

src/panels/config/areas/ha-config-areas.ts

@@ -45,7 +45,7 @@ export class HaConfigAreas extends LitElement {
     }
   }
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     if (!this.hass || this._areas === undefined) {
       return html`
         <hass-loading-screen></hass-loading-screen>

src/panels/config/automation/ha-automation-editor.ts

@@ -45,7 +45,7 @@ export class HaAutomationEditor extends LitElement {
   @property() private _dirty?: boolean;
   @property() private _errors?: string;
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     return html`
       <ha-app-layout has-scrolling-region>
         <app-header slot="header" fixed>

src/panels/config/automation/ha-automation-picker.ts

@@ -39,7 +39,7 @@ class HaAutomationPicker extends LitElement {
   @property() public isWide!: boolean;
   @property() public automations!: AutomationEntity[];
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     return html`
       <hass-subpage
         .showBackButton=${!this.isWide}

src/panels/config/automation/thingtalk/dialog-thingtalk.ts

@@ -58,7 +58,7 @@ class DialogThingtalk extends LitElement {
     this._opened = true;
   }
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     if (!this._params) {
       return html``;
     }

src/panels/config/automation/thingtalk/ha-thingtalk-placeholders.ts

@@ -112,7 +112,7 @@ export class ThingTalkPlaceholders extends SubscribeMixin(LitElement) {
     }
   }
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     return html`
       <ha-paper-dialog
         modal

src/panels/config/cloud/account/cloud-alexa-pref.ts

@@ -23,7 +23,7 @@ export class CloudAlexaPref extends LitElement {
   @property() public cloudStatus?: CloudStatusLoggedIn;
   @property() private _syncing = false;
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     if (!this.cloudStatus) {
       return html``;
     }

src/panels/config/cloud/account/cloud-google-pref.ts

@@ -24,7 +24,7 @@ export class CloudGooglePref extends LitElement {
   @property() public hass?: HomeAssistant;
   @property() public cloudStatus?: CloudStatusLoggedIn;
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     if (!this.cloudStatus) {
       return html``;
     }

src/panels/config/cloud/account/cloud-remote-pref.ts

@@ -29,7 +29,7 @@ export class CloudRemotePref extends LitElement {
   @property() public hass?: HomeAssistant;
   @property() public cloudStatus?: CloudStatusLoggedIn;
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     if (!this.cloudStatus) {
       return html``;
     }

src/panels/config/cloud/alexa/cloud-alexa.ts

@@ -72,7 +72,7 @@ class CloudAlexa extends LitElement {
     )
   );
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     if (this._entities === undefined) {
       return html`
         <hass-loading-screen></hass-loading-screen>

src/panels/config/cloud/google-assistant/cloud-google-assistant.ts

@@ -71,7 +71,7 @@ class CloudGoogleAssistant extends LitElement {
     )
   );
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     if (this._entities === undefined) {
       return html`
         <hass-loading-screen></hass-loading-screen>

src/panels/config/core/ha-config-core-form.ts

@@ -33,7 +33,7 @@ class ConfigCoreForm extends LitElement {
   @property() private _unitSystem!: ConfigUpdateValues["unit_system"];
   @property() private _timeZone!: string;
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     const canEdit = ["storage", "default"].includes(
       this.hass.config.config_source
     );

src/panels/config/core/ha-config-name-form.ts

@@ -24,7 +24,7 @@ class ConfigNameForm extends LitElement {
 
   @property() private _name!: ConfigUpdateValues["location_name"];
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     const canEdit = ["storage", "default"].includes(
       this.hass.config.config_source
     );

src/panels/config/dashboard/ha-config-dashboard.ts

@@ -32,7 +32,7 @@ class HaConfigDashboard extends LitElement {
   @property() public cloudStatus?: CloudStatus;
   @property() public showAdvanced!: boolean;
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     return html`
       <app-header-layout has-scrolling-region>
         <app-header fixed slot="header">

src/panels/config/dashboard/ha-config-navigation.ts

@@ -32,7 +32,7 @@ class HaConfigNavigation extends LitElement {
   @property() public pages!: ConfigPageNavigation[];
   @property() public curPage!: string;
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     return html`
       <paper-listbox attr-for-selected="data-page" .selected=${this.curPage}>
         ${this.pages.map(({ page, core, advanced, info }) =>

src/panels/config/entities/dialog-entity-registry-detail.ts

@@ -46,7 +46,7 @@ export class DialogEntityRegistryDetail extends LitElement {
     this._params = undefined;
   }
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     if (!this._params) {
       return html``;
     }

src/panels/config/entities/entity-registry-settings.ts

@@ -41,6 +41,7 @@ export class EntityRegistrySettings extends LitElement {
   private _origEntityId!: string;
 
   protected updated(changedProperties: PropertyValues) {
+    super.updated(changedProperties);
     if (changedProperties.has("entry")) {
       this._error = undefined;
       this._name = this.entry.name || "";
@@ -50,9 +51,9 @@ export class EntityRegistrySettings extends LitElement {
     }
   }
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     if (this.entry.entity_id !== this._origEntityId) {
-      return;
+      return html``;
     }
     const stateObj: HassEntity | undefined = this.hass.states[
       this.entry.entity_id

src/panels/config/entities/ha-config-entities.ts

@@ -217,7 +217,7 @@ export class HaConfigEntities extends SubscribeMixin(LitElement) {
     dialog.closeDialog();
   }
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     if (!this.hass || this._entities === undefined) {
       return html`
         <hass-loading-screen></hass-loading-screen>

src/panels/config/integrations/ha-config-entries-dashboard.ts

@@ -334,6 +334,7 @@ export class HaConfigManagerDashboard extends LitElement {
     });
     return states;
   }
+
   static get styles(): CSSResult {
     return css`
       ha-card {

src/panels/config/person/dialog-person-detail.ts

@@ -50,7 +50,7 @@ class DialogPersonDetail extends LitElement {
     await this.updateComplete;
   }
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     if (!this._params) {
       return html``;
     }

src/panels/config/person/ha-config-person.ts

@@ -36,7 +36,7 @@ class HaConfigPerson extends LitElement {
   @property() private _configItems?: Person[];
   private _usersLoad?: Promise<User[]>;
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     if (
       !this.hass ||
       this._storageItems === undefined ||

src/panels/config/scene/ha-scene-dashboard.ts

@@ -33,7 +33,7 @@ class HaSceneDashboard extends LitElement {
   @property() public isWide!: boolean;
   @property() public scenes!: SceneEntity[];
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     return html`
       <hass-subpage
         .showBackButton=${!this.isWide}

src/panels/config/scene/ha-scene-editor.ts

@@ -146,9 +146,9 @@ export class HaSceneEditor extends SubscribeMixin(LitElement) {
     ];
   }
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     if (!this.hass) {
-      return;
+      return html``;
     }
     const { devices, entities } = this._getEntitiesDevices(
       this._entities,

src/panels/config/script/ha-script-editor.ts

@@ -38,7 +38,7 @@ export class HaScriptEditor extends LitElement {
   @property() private _dirty?: boolean;
   @property() private _errors?: string;
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     return html`
       <ha-app-layout has-scrolling-region>
         <app-header slot="header" fixed>

src/panels/config/script/ha-script-picker.ts

@@ -32,7 +32,7 @@ class HaScriptPicker extends LitElement {
   @property() public scripts!: HassEntity[];
   @property() public isWide!: boolean;
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     return html`
       <hass-subpage
         .showBackButton=${!this.isWide}

src/panels/config/users/ha-user-editor.ts

@@ -43,7 +43,7 @@ class HaUserEditor extends LitElement {
   @property() public hass?: HomeAssistant;
   @property() public user?: User;
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     const hass = this.hass;
     const user = this.user;
     if (!hass || !user) {

src/panels/config/zha/zha-add-devices-page.ts

@@ -50,7 +50,7 @@ class ZHAAddDevicesPage extends LitElement {
     this._formattedEvents = "";
   }
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     return html`
       <hass-subpage
         header="${this.hass!.localize(

src/panels/config/zha/zha-cluster-attributes.ts

@@ -58,7 +58,7 @@ export class ZHAClusterAttributes extends LitElement {
     super.update(changedProperties);
   }
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     return html`
       <ha-config-section .isWide="${this.isWide}">
         <div class="header" slot="header">

src/panels/config/zha/zha-cluster-commands.ts

@@ -53,7 +53,7 @@ export class ZHAClusterCommands extends LitElement {
     super.update(changedProperties);
   }
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     return html`
       <ha-config-section .isWide="${this.isWide}">
         <div class="header" slot="header">

src/panels/config/zha/zha-clusters.ts

@@ -53,7 +53,7 @@ export class ZHAClusters extends LitElement {
     super.update(changedProperties);
   }
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     return html`
       <ha-config-section .isWide="${this.isWide}">
         <div class="header" slot="header">

src/panels/config/zha/zha-config-dashboard.ts

@@ -100,7 +100,7 @@ class ZHAConfigDashboard extends LitElement {
     this._firstUpdatedCalled = true;
   }
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     return html`
       <hass-subpage
         .header=${this.hass.localize("ui.panel.config.zha.title")}

src/panels/config/zha/zha-device-binding.ts

@@ -41,7 +41,7 @@ export class ZHADeviceBindingControl extends LitElement {
     super.update(changedProperties);
   }
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     return html`
       <ha-config-section .isWide="${this.isWide}">
         <div class="header" slot="header">

src/panels/config/zha/zha-device-card.ts

@@ -139,7 +139,7 @@ class ZHADeviceCard extends LitElement {
     }
   }
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     return html`
       <ha-card header="${this.showName ? this.device!.name : ""}">
         ${

src/panels/config/zha/zha-device-page.ts

@@ -68,7 +68,7 @@ export class ZHADevicePage extends LitElement {
     super.update(changedProperties);
   }
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     return html`
       <hass-subpage
         .header=${this.hass!.localize("ui.panel.config.zha.devices.header")}

src/panels/config/zha/zha-group-binding.ts

@@ -57,7 +57,7 @@ export class ZHAGroupBindingControl extends LitElement {
     super.update(changedProperties);
   }
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     return html`
       <ha-config-section .isWide="${this.isWide}">
         <div class="sectionHeader" slot="header">

src/panels/config/zha/zha-node.ts

@@ -27,7 +27,7 @@ export class ZHANode extends LitElement {
   @property() public device?: ZHADevice;
   @property() private _showHelp: boolean = false;
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     return html`
       <ha-config-section .isWide="${this.isWide}">
         <div class="header" slot="header">

src/panels/config/zone/dialog-zone-detail.ts

@@ -58,7 +58,7 @@ class DialogZoneDetail extends LitElement {
     await this.updateComplete;
   }
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     if (!this._params) {
       return html``;
     }

src/panels/config/zone/ha-config-zone.ts

@@ -95,7 +95,7 @@ export class HaConfigZone extends SubscribeMixin(LitElement) {
     ];
   }
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     if (
       !this.hass ||
       this._storageItems === undefined ||

src/panels/config/zwave/zwave-network.ts

@@ -48,7 +48,7 @@ export class ZwaveNetwork extends LitElement {
     this._subscribe();
   }
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     return html`
       <ha-config-section .isWide="${this.isWide}">
         <div class="sectionHeader" slot="header">

src/panels/config/zwave/zwave-node-config.ts

@@ -37,7 +37,7 @@ export class ZwaveNodeConfig extends LitElement {
   @property() private _selectedConfigParameter: number = -1;
   @property() private _selectedConfigValue: number | string = -1;
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     return html`
       <div class="content">
         <ha-card

src/panels/config/zwave/zwave-values.ts

@@ -26,7 +26,7 @@ export class ZwaveValues extends LitElement {
   @property() public values: ZWaveValue[] = [];
   @property() private _selectedValue: number = -1;
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     return html`
       <div class="content">
         <ha-card

src/panels/developer-tools/ha-panel-developer-tools.ts

@@ -30,7 +30,7 @@ class PanelDeveloperTools extends LitElement {
   @property() public route!: Route;
   @property() public narrow!: boolean;
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     const page = this._page;
     return html`
       <app-header-layout has-scrolling-region>

src/panels/developer-tools/info/developer-tools-info.ts

@@ -19,7 +19,7 @@ const OPT_IN_PANEL = "states";
 class HaPanelDevInfo extends LitElement {
   @property() public hass!: HomeAssistant;
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     const hass = this.hass;
     const customUiList: Array<{ name: string; url: string; version: string }> =
       (window as any).CUSTOM_UI_LIST || [];

src/panels/developer-tools/info/system-health-card.ts

@@ -35,9 +35,9 @@ class SystemHealthCard extends LitElement {
   @property() public hass!: HomeAssistant;
   @property() private _info?: SystemHealthInfo;
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     if (!this.hass) {
-      return;
+      return html``;
     }
     const sections: TemplateResult[] = [];
 

src/panels/developer-tools/logs/developer-tools-logs.ts

@@ -30,7 +30,7 @@ export class HaPanelDevLogs extends LitElement {
     }
   }
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     return html`
       <div class="content">
         <system-log-card .hass=${this.hass}></system-log-card>

src/panels/developer-tools/logs/dialog-system-log-detail.ts

@@ -24,7 +24,7 @@ class DialogSystemLogDetail extends LitElement {
     await this.updateComplete;
   }
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     if (!this._params) {
       return html``;
     }

src/panels/developer-tools/logs/error-log-card.ts

@@ -16,7 +16,7 @@ class ErrorLogCard extends LitElement {
   @property() public hass!: HomeAssistant;
   @property() private _errorLog?: string;
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     return html`
       <p class="error-log-intro">
         ${this._errorLog

src/panels/developer-tools/logs/system-log-card.ts

@@ -41,7 +41,7 @@ export class SystemLogCard extends LitElement {
     this._items = await fetchSystemLog(this.hass!);
   }
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     return html`
       <div class="system-log-intro">
         <ha-card>

src/panels/logbook/ha-logbook.ts

@@ -41,7 +41,7 @@ class HaLogbook extends LitElement {
     this._rtl = computeRTL(this.hass);
   }
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     if (!this.entries?.length) {
       return html`
         ${this.hass.localize("ui.panel.logbook.entries_not_found")}

src/panels/lovelace/badges/hui-error-badge.ts

@@ -35,7 +35,7 @@ export class HuiErrorBadge extends LitElement implements LovelaceBadge {
     this._config = config;
   }
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     if (!this._config) {
       return html``;
     }

src/panels/lovelace/badges/hui-state-label-badge.ts

@@ -29,7 +29,7 @@ export class HuiStateLabelBadge extends LitElement implements LovelaceBadge {
     this._config = config;
   }
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     if (!this._config || !this.hass) {
       return html``;
     }

src/panels/lovelace/cards/hui-alarm-panel-card.ts

@@ -124,7 +124,7 @@ class HuiAlarmPanelCard extends LitElement implements LovelaceCard {
     );
   }
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     if (!this._config || !this.hass) {
       return html``;
     }

src/panels/lovelace/cards/hui-empty-state-card.ts

@@ -26,7 +26,7 @@ export class HuiEmptyStateCard extends LitElement implements LovelaceCard {
     // tslint:disable-next-line
   }
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     if (!this.hass) {
       return html``;
     }

src/panels/lovelace/cards/hui-entities-card.ts

@@ -100,7 +100,7 @@ class HuiEntitiesCard extends LitElement implements LovelaceCard {
     }
   }
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     if (!this._config || !this._hass) {
       return html``;
     }

src/panels/lovelace/cards/hui-entity-button-card.ts

@@ -112,7 +112,7 @@ class HuiEntityButtonCard extends LitElement implements LovelaceCard {
     );
   }
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     if (!this._config || !this.hass) {
       return html``;
     }

src/panels/lovelace/cards/hui-error-card.ts

@@ -39,7 +39,7 @@ export class HuiErrorCard extends LitElement implements LovelaceCard {
     this._config = config;
   }
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     if (!this._config) {
       return html``;
     }

src/panels/lovelace/cards/hui-gauge-card.ts

@@ -68,7 +68,7 @@ class HuiGaugeCard extends LitElement implements LovelaceCard {
     this._setBaseUnit();
   }
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     if (!this._config || !this.hass) {
       return html``;
     }

src/panels/lovelace/cards/hui-glance-card.ts

@@ -110,7 +110,7 @@ export class HuiGlanceCard extends LitElement implements LovelaceCard {
     return false;
   }
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     if (!this._config || !this.hass) {
       return html``;
     }

src/panels/lovelace/cards/hui-iframe-card.ts

@@ -46,7 +46,7 @@ export class HuiIframeCard extends LitElement implements LovelaceCard {
     this._config = config;
   }
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     if (!this._config) {
       return html``;
     }

src/panels/lovelace/cards/hui-light-card.ts

@@ -60,7 +60,7 @@ export class HuiLightCard extends LitElement implements LovelaceCard {
     this._config = { theme: "default", ...config };
   }
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     if (!this.hass || !this._config) {
       return html``;
     }

src/panels/lovelace/cards/hui-map-card.ts

@@ -135,7 +135,7 @@ class HuiMapCard extends LitElement implements LovelaceCard {
     }
   }
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     if (!this._config) {
       return html``;
     }

src/panels/lovelace/cards/hui-markdown-card.ts

@@ -71,7 +71,7 @@ export class HuiMarkdownCard extends LitElement implements LovelaceCard {
     this._connect();
   }
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     if (!this._config) {
       return html``;
     }

src/panels/lovelace/cards/hui-picture-card.ts

@@ -75,7 +75,7 @@ export class HuiPictureCard extends LitElement implements LovelaceCard {
     }
   }
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     if (!this._config || !this.hass) {
       return html``;
     }

src/panels/lovelace/cards/hui-picture-elements-card.ts

@@ -71,7 +71,7 @@ class HuiPictureElementsCard extends LitElement implements LovelaceCard {
     }
   }
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     if (!this._config) {
       return html``;
     }

src/panels/lovelace/cards/hui-picture-entity-card.ts

@@ -95,7 +95,7 @@ class HuiPictureEntityCard extends LitElement implements LovelaceCard {
     }
   }
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     if (!this._config || !this.hass) {
       return html``;
     }

src/panels/lovelace/cards/hui-picture-glance-card.ts

@@ -149,7 +149,7 @@ class HuiPictureGlanceCard extends LitElement implements LovelaceCard {
     }
   }
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     if (!this._config || !this.hass) {
       return html``;
     }

src/panels/lovelace/cards/hui-plant-status-card.ts

@@ -84,7 +84,7 @@ class HuiPlantStatusCard extends LitElement implements LovelaceCard {
     }
   }
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     if (!this.hass || !this._config) {
       return html``;
     }

src/panels/lovelace/cards/hui-sensor-card.ts

@@ -191,7 +191,7 @@ class HuiSensorCard extends LitElement implements LovelaceCard {
     return 3;
   }
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     if (!this._config || !this.hass) {
       return html``;
     }

src/panels/lovelace/cards/hui-shopping-list-card.ts

@@ -102,7 +102,7 @@ class HuiShoppingListCard extends LitElement implements LovelaceCard {
     }
   }
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     if (!this._config || !this.hass) {
       return html``;
     }

src/panels/lovelace/cards/hui-stack-card.ts

@@ -41,7 +41,7 @@ export abstract class HuiStackCard extends LitElement implements LovelaceCard {
     });
   }
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     if (!this._config) {
       return html``;
     }

src/panels/lovelace/cards/hui-thermostat-card.ts

@@ -83,7 +83,7 @@ export class HuiThermostatCard extends LitElement implements LovelaceCard {
     this.rescale_svg();
   }
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     if (!this.hass || !this._config) {
       return html``;
     }

src/panels/lovelace/cards/hui-weather-forecast-card.ts

@@ -118,7 +118,7 @@ class HuiWeatherForecastCard extends LitElement implements LovelaceCard {
     }
   }
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     if (!this._config || !this.hass) {
       return html``;
     }

src/panels/lovelace/components/hui-action-editor.ts

@@ -62,7 +62,7 @@ export class HuiActionEditor extends LitElement {
     return config.service || "";
   }
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     if (!this.hass || !this.actions) {
       return html``;
     }

src/panels/lovelace/components/hui-card-options.ts

@@ -30,7 +30,7 @@ export class HuiCardOptions extends LitElement {
 
   @property() public path?: [number, number];
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     return html`
       <slot></slot>
       <div class="options">

src/panels/lovelace/components/hui-entities-toggle.ts

@@ -37,7 +37,7 @@ class HuiEntitiesToggle extends LitElement {
     }
   }
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     if (!this._toggleEntities) {
       return html``;
     }

src/panels/lovelace/components/hui-entity-editor.ts

@@ -24,7 +24,7 @@ export class HuiEntityEditor extends LitElement {
 
   @property() protected label?: string;
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     if (!this.entities) {
       return html``;
     }

src/panels/lovelace/components/hui-generic-entity-row.ts

@@ -34,7 +34,7 @@ class HuiGenericEntityRow extends LitElement {
 
   @property() public showSecondary: boolean = true;
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     if (!this.hass || !this.config) {
       return html``;
     }

src/panels/lovelace/components/hui-image.ts

@@ -70,7 +70,7 @@ export class HuiImage extends LitElement {
     this._stopUpdateCameraInterval();
   }
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     const ratio = this.aspectRatio ? parseAspectRatio(this.aspectRatio) : null;
     const stateObj =
       this.hass && this.entity ? this.hass.states[this.entity] : undefined;

src/panels/lovelace/components/hui-input-list-editor.ts

@@ -20,7 +20,7 @@ export class HuiInputListEditor extends LitElement {
   @property() protected hass?: HomeAssistant;
   @property() protected inputLabel?: string;
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     if (!this.value) {
       return html``;
     }

src/panels/lovelace/components/hui-theme-select-editor.ts

@@ -29,7 +29,7 @@ export class HuiThemeSelectEditor extends LitElement {
   @property() public label?: string;
   @property() public hass?: HomeAssistant;
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     const themes = ["Backend-selected", "default"].concat(
       Object.keys(this.hass!.themes.themes).sort()
     );

src/panels/lovelace/components/hui-timestamp-display.ts

@@ -51,7 +51,7 @@ class HuiTimestampDisplay extends LitElement {
     this._clearInterval();
   }
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     if (!this.ts || !this.hass) {
       return html``;
     }

src/panels/lovelace/components/hui-unavailable.ts

@@ -12,7 +12,7 @@ import {
 export class HuiUnavailable extends LitElement {
   @property() public text?: string;
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     return html`
       <div class="disabled-overlay">
         <div>${this.text}</div>

src/panels/lovelace/components/hui-views-list.ts

@@ -27,7 +27,7 @@ class HuiViewsList extends LitElement {
   @property() private lovelaceConfig?: LovelaceConfig | undefined;
   @property() private selected?: number | undefined;
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     if (!this.lovelaceConfig) {
       return html``;
     }

src/panels/lovelace/components/hui-warning-element.ts

@@ -14,7 +14,7 @@ import "../../../components/ha-icon";
 export class HuiWarningElement extends LitElement {
   @property() public label?: string;
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     return html`
       <ha-icon icon="hass:alert" .title="${this.label}"></ha-icon>
     `;

src/panels/lovelace/components/hui-warning.ts

@@ -9,7 +9,7 @@ import {
 
 @customElement("hui-warning")
 export class HuiWarning extends LitElement {
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     return html`
       <slot></slot>
     `;

src/panels/lovelace/editor/card-editor/hui-card-picker.ts

@@ -47,7 +47,7 @@ export class HuiCardPicker extends LitElement {
 
   public cardPicked?: (cardConf: LovelaceCardConfig) => void;
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     return html`
       <div class="cards-container">
         ${cards.map((card: string) => {

src/panels/lovelace/editor/card-editor/hui-dialog-edit-card.ts

@@ -61,7 +61,7 @@ export class HuiDialogEditCard extends LitElement {
     return this.shadowRoot!.querySelector("hui-card-editor");
   }
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     if (!this._params) {
       return html``;
     }

src/panels/lovelace/editor/card-editor/hui-dialog-move-card-view.ts

@@ -27,7 +27,7 @@ export class HuiDialogMoveCardView extends LitElement {
     await this.updateComplete;
   }
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     if (!this._params) {
       return html``;
     }

src/panels/lovelace/editor/card-editor/hui-dialog-suggest-card.ts

@@ -60,7 +60,7 @@ export class HuiDialogSuggestCard extends LitElement {
     }
   }
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     return html`
       <ha-paper-dialog with-backdrop opened>
         <h2>

src/panels/lovelace/editor/config-elements/hui-alarm-panel-card-editor.ts

@@ -59,7 +59,7 @@ export class HuiAlarmPanelCardEditor extends LitElement
     return this._config!.theme || "Backend-selected";
   }
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     if (!this.hass) {
       return html``;
     }

src/panels/lovelace/editor/config-elements/hui-entities-card-editor.ts

@@ -66,7 +66,7 @@ export class HuiEntitiesCardEditor extends LitElement
     return this._config!.theme || "Backend-selected";
   }
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     if (!this.hass) {
       return html``;
     }

src/panels/lovelace/editor/config-elements/hui-entity-button-card-editor.ts

@@ -87,7 +87,7 @@ export class HuiEntityButtonCardEditor extends LitElement
     return this._config!.theme || "default";
   }
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     if (!this.hass) {
       return html``;
     }

src/panels/lovelace/editor/config-elements/hui-gauge-card-editor.ts

@@ -72,7 +72,7 @@ export class HuiGaugeCardEditor extends LitElement
     return this._config!.severity || undefined;
   }
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     if (!this.hass) {
       return html``;
     }

src/panels/lovelace/editor/config-elements/hui-glance-card-editor.ts

@@ -79,7 +79,7 @@ export class HuiGlanceCardEditor extends LitElement
     return this._config!.show_state || true;
   }
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     if (!this.hass) {
       return html``;
     }

src/panels/lovelace/editor/config-elements/hui-history-graph-card-editor.ts

@@ -66,7 +66,7 @@ export class HuiHistoryGraphCardEditor extends LitElement
     return this._config!.refresh_interval || 0;
   }
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     if (!this.hass) {
       return html``;
     }

src/panels/lovelace/editor/config-elements/hui-iframe-card-editor.ts

@@ -46,7 +46,7 @@ export class HuiIframeCardEditor extends LitElement
     return this._config!.aspect_ratio || "";
   }
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     if (!this.hass) {
       return html``;
     }

src/panels/lovelace/editor/config-elements/hui-light-card-editor.ts

@@ -54,7 +54,7 @@ export class HuiLightCardEditor extends LitElement
     return this._config!.icon || "";
   }
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     if (!this.hass) {
       return html``;
     }

src/panels/lovelace/editor/config-elements/hui-map-card-editor.ts

@@ -71,7 +71,7 @@ export class HuiMapCardEditor extends LitElement implements LovelaceCardEditor {
     return this._config!.dark_mode || false;
   }
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     if (!this.hass) {
       return html``;
     }

src/panels/lovelace/editor/config-elements/hui-markdown-card-editor.ts

@@ -49,7 +49,7 @@ export class HuiMarkdownCardEditor extends LitElement
     return this._config!.theme || "Backend-selected";
   }
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     if (!this.hass) {
       return html``;
     }

src/panels/lovelace/editor/config-elements/hui-media-control-card-editor.ts

@@ -36,7 +36,7 @@ export class HuiMediaControlCardEditor extends LitElement
     return this._config!.entity || "";
   }
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     if (!this.hass) {
       return html``;
     }

src/panels/lovelace/editor/config-elements/hui-picture-card-editor.ts

@@ -59,7 +59,7 @@ export class HuiPictureCardEditor extends LitElement
     return this._config!.theme || "Backend-selected";
   }
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     if (!this.hass) {
       return html``;
     }

src/panels/lovelace/editor/config-elements/hui-picture-entity-card-editor.ts

@@ -99,7 +99,7 @@ export class HuiPictureEntityCardEditor extends LitElement
     return this._config!.theme || "Backend-selected";
   }
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     if (!this.hass) {
       return html``;
     }

src/panels/lovelace/editor/config-elements/hui-picture-glance-card-editor.ts

@@ -110,7 +110,7 @@ export class HuiPictureGlanceCardEditor extends LitElement
     return this._config!.theme || "Backend-selected";
   }
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     if (!this.hass) {
       return html``;
     }

src/panels/lovelace/editor/config-elements/hui-plant-status-card-editor.ts

@@ -50,7 +50,7 @@ export class HuiPlantStatusCardEditor extends LitElement
     return this._config!.theme || "Backend-selected";
   }
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     if (!this.hass) {
       return html``;
     }

src/panels/lovelace/editor/config-elements/hui-sensor-card-editor.ts

@@ -77,7 +77,7 @@ export class HuiSensorCardEditor extends LitElement
     return this._config!.hours_to_show || "24";
   }
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     if (!this.hass) {
       return html``;
     }

src/panels/lovelace/editor/config-elements/hui-shopping-list-editor.ts

@@ -45,7 +45,7 @@ export class HuiShoppingListEditor extends LitElement
     return this._config!.theme || "Backend-selected";
   }
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     if (!this.hass) {
       return html``;
     }

src/panels/lovelace/editor/config-elements/hui-thermostat-card-editor.ts

@@ -49,7 +49,7 @@ export class HuiThermostatCardEditor extends LitElement
     return this._config!.theme || "default";
   }
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     if (!this.hass) {
       return html``;
     }

src/panels/lovelace/editor/config-elements/hui-weather-forecast-card-editor.ts

@@ -48,7 +48,7 @@ export class HuiWeatherForecastCardEditor extends LitElement
     return this._config!.theme || "Backend-selected";
   }
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     if (!this.hass) {
       return html``;
     }

src/panels/lovelace/editor/hui-dialog-save-config.ts

@@ -40,7 +40,7 @@ export class HuiSaveConfig extends LitElement {
     return this.shadowRoot!.querySelector("ha-paper-dialog")!;
   }
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     return html`
       <ha-paper-dialog with-backdrop>
         <h2>

src/panels/lovelace/editor/lovelace-editor/hui-dialog-edit-lovelace.ts

@@ -52,7 +52,7 @@ export class HuiDialogEditLovelace extends LitElement {
     return this.shadowRoot!.querySelector("ha-paper-dialog")!;
   }
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     return html`
       <ha-paper-dialog with-backdrop modal>
         <h2>

src/panels/lovelace/editor/lovelace-editor/hui-lovelace-editor.ts

@@ -35,7 +35,7 @@ export class HuiLovelaceEditor extends LitElement {
     return this.config.title || "";
   }
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     return html`
       ${configElementStyle}
       <div class="card-config">

src/panels/lovelace/editor/select-view/hui-dialog-select-view.ts

@@ -36,7 +36,7 @@ export class HuiDialogSelectView extends LitElement {
     );
   }
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     if (!this._params) {
       return html``;
     }

src/panels/lovelace/editor/unused-entities/hui-unused-entities.ts

@@ -112,7 +112,7 @@ export class HuiUnusedEntities extends LitElement {
     }
   }
 
-  protected render(): TemplateResult | void {
+  protected render(): TemplateResult {
     if (!this.hass || !this.lovelace) {
       return html``;
     }