Fix messaging delete bug

Author: hsubox76

packages-exp/messaging-exp/src/messaging-service.ts

@@ -27,7 +27,7 @@ import { extractAppConfig } from './helpers/extract-app-config';
 export class MessagingService implements _FirebaseService {
   readonly app!: FirebaseApp;
   readonly firebaseDependencies!: FirebaseInternalDependencies;
-  deleteService!: () => Promise<void>;
+  deleteService: () => Promise<void> = () => Promise.resolve();
 
   swRegistration?: ServiceWorkerRegistration;
   vapidKey?: string;