Cast: Show error message instead of number (#3752)

* Cast: Show error message instead of number

* Update hc-main.ts

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

@@ -137,14 +137,14 @@ export class HcMain extends HassElement {
         }),
       });
     } catch (err) {
-      this._error = err;
+      this._error = this._getErrorMessage(err);
       return;
     }
     let connection;
     try {
       connection = await createConnection({ auth });
     } catch (err) {
-      this._error = err;
+      this._error = this._getErrorMessage(err);
       return;
     }
     if (this.hass) {
@@ -213,6 +213,23 @@ export class HcMain extends HassElement {
     });
   }
 
+  private _getErrorMessage(error: number): string {
+    switch (error) {
+      case 1:
+        return "Unable to connect to the Home Assistant websocket API.";
+      case 2:
+        return "The supplied authentication is invalid.";
+      case 3:
+        return "The connection to Home Assistant was lost.";
+      case 4:
+        return "Missing hassUrl. This is required.";
+      case 5:
+        return "Home Assistant needs to be served over https:// to use with Home Assistant Cast.";
+      default:
+        return "Unknown Error";
+    }
+  }
+
   private _breakFree() {
     const controls = document.body.querySelector("touch-controls");
     if (controls) {