Show error if no OZW instances are detected (#7176)

src/panels/config/integrations/integration-panels/ozw/ozw-config-dashboard.ts

@@ -28,6 +28,8 @@ import type { PageNavigation } from "../../../../../layouts/hass-tabs-subpage";
 import { haStyle } from "../../../../../resources/styles";
 import type { HomeAssistant, Route } from "../../../../../types";
 import "../../../ha-config-section";
+import "../../../../../layouts/hass-error-screen";
+import "../../../../../layouts/hass-loading-screen";
 
 export const ozwTabs: PageNavigation[] = [];
 
@@ -43,13 +45,25 @@ class OZWConfigDashboard extends LitElement {
 
   @property() public configEntryId?: string;
 
-  @internalProperty() private _instances: OZWInstance[] = [];
+  @internalProperty() private _instances?: OZWInstance[];
 
   protected firstUpdated() {
     this._fetchData();
   }
 
   protected render(): TemplateResult {
+    if (!this._instances) {
+      return html`<hass-loading-screen></hass-loading-screen>`;
+    }
+
+    if (this._instances.length === 0) {
+      return html`<hass-error-screen
+        .error="${this.hass.localize(
+          "ui.panel.config.ozw.select_instance.none_found"
+        )}"
+      ></hass-error-screen>`;
+    }
+
     return html`
       <hass-tabs-subpage
         .hass=${this.hass}

src/translations/en.json

@@ -1894,7 +1894,8 @@
           },
           "select_instance": {
             "header": "Select an OpenZWave Instance",
-            "introduction": "You have more than one OpenZWave instance running. Which instance would you like to manage?"
+            "introduction": "You have more than one OpenZWave instance running. Which instance would you like to manage?",
+            "none_found": "We couldn't find an OpenZWave instance. If you believe this is incorrect, check your OpenZWave and MQTT setups and ensure that Home Assistant can communicate with your MQTT broker."
           },
           "network": {
             "header": "Network Management",