[PM-12007] Fix vault timeout action logout with account switching (#11008)

* Protect Against Toast Error

* Use `concatMap` Instead of `switchMap`

apps/browser/src/popup/app.component.ts

@@ -247,7 +247,7 @@ export class AppComponent implements OnInit, OnDestroy {
   // Displaying toasts isn't super useful on the popup due to the reloads we do.
   // However, it is visible for a moment on the FF sidebar logout.
   private async displayLogoutReason(logoutReason: LogoutReason) {
-    let toastOptions: ToastOptions;
+    let toastOptions: ToastOptions | null = null;
     switch (logoutReason) {
       case "invalidSecurityStamp":
       case "sessionExpired": {
@@ -260,6 +260,11 @@ export class AppComponent implements OnInit, OnDestroy {
       }
     }
 
+    if (toastOptions == null) {
+      // We don't have anything to show for this particular reason
+      return;
+    }
+
     this.toastService.showToast(toastOptions);
   }
 }