Catch and retry if getting Firebase Messing token failed (#869)

Fixes #868

app/lib/util/notification_token_adder.dart

@@ -10,6 +10,7 @@ import 'dart:developer';
 
 import 'package:collection/collection.dart';
 import 'package:firebase_messaging/firebase_messaging.dart';
+import 'package:retry/retry.dart';
 import 'package:sharezone/main/sharezone.dart';
 import 'package:sharezone/util/api/user_api.dart';
 
@@ -59,7 +60,19 @@ class NotificationTokenAdderApi {
       return null;
     }
 
-    return _firebaseMessaging.getToken(vapidKey: vapidKey);
+    try {
+      // Retry because sometimes we get an unknown error from Firebase
+      // Messaging.
+      //
+      // See https://console.firebase.google.com/u/0/project/sharezone-c2bd8/crashlytics/app/ios:de.codingbrain.sharezone.app/issues/bd7d15551a69ad54ea806f4627d8eeda
+      return retry<String?>(
+        () => _firebaseMessaging.getToken(vapidKey: vapidKey),
+        maxAttempts: 3,
+      );
+    } catch (e, s) {
+      log('Could not get FCM token', error: e, stackTrace: s);
+      return null;
+    }
   }
 
   Future<void> tryAddTokenToDatabase(String token) async {

app/pubspec.lock

@@ -1682,7 +1682,7 @@ packages:
     source: path
     version: "0.0.1"
   retry:
-    dependency: transitive
+    dependency: "direct main"
     description:
       name: retry
       sha256: "822e118d5b3aafed083109c72d5f484c6dc66707885e07c0fbcb8b986bba7efc"

app/pubspec.yaml

@@ -132,6 +132,7 @@ dependencies:
   quiver: ^3.0.1
   remote_configuration:
     path: ../lib/remote_configuration
+  retry: ^3.1.2
   rxdart: ^0.27.1
   scrollable_positioned_list: ^0.3.8
   share: ^2.0.4