Flutter Google Войти - данные электронной почты возвращает ноль

Question

Flutter Google Войти - данные электронной почты возвращает ноль. Логи приведены ниже. Заранее большое спасибо.

Я использую Firebase.

Я хочу войти в систему с помощью Google, но AuthResult.user.email == null

------------------------ Ошибка журнала ---------------- ------------

D/FirebaseAuth( 5302): Notifying id token listeners about user ( 9uKLCYS4VwUbuu77KS27bWjKrlI2 ).
I/flutter ( 5302): Result : Poyraz Çakmak https://lh3.googleusercontent.com/a-/AAuE7mABS7DqwgoIHuFfIwNw_574FRdvxKuvVyNarFo0_w=s96-c null
I/flutter ( 5302): NoSuchMethodError: The method 'indexOf' was called on null.
I/flutter ( 5302): Receiver: null
I/flutter ( 5302): Tried calling: indexOf("@")

, поскольку модель пользователя из формата userName. => Пробный вызов: indexOf ("@")

Метод GoogleSignIn:

@override
Future<User> login() async {
final GoogleSignInAccount googleSignInAccount =
    await MyToolsFirebase.googleSignIn.signIn();

if (googleSignInAccount != null) {
  GoogleSignInAuthentication googleSignInAuthentication =
      await googleSignInAccount.authentication;

  final String idToken = googleSignInAuthentication.idToken;
  final String accessToken = googleSignInAuthentication.accessToken;

  if (idToken != null && accessToken != null) {
    AuthResult authResult = await MyToolsFirebase.firebaseAuth
        .signInWithCredential(GoogleAuthProvider.getCredential(
            idToken: idToken, accessToken: accessToken));

    return await MyToolsFirebase.saveDbUser(firebaseUser: authResult.user);
  }
}
return null;
}

Класс MyToolsFirebase:

import 'package:cloud_firestore/cloud_firestore.dart';
import 'package:firebase_auth/firebase_auth.dart';
import 'package:google_sign_in/google_sign_in.dart';
import 'package:live_chat/Models/User.dart';

class MyToolsFirebase {

  static final FirebaseAuth firebaseAuth = FirebaseAuth.instance;

  static final GoogleSignIn googleSignIn = GoogleSignIn(
    scopes: <String>[
      'https://www.googleapis.com/auth/contacts.readonly',
      'https://www.googleapis.com/auth/plus.login',
      'https://www.googleapis.com/auth/userinfo.email'
    ],
  );

  static final Firestore firestore = Firestore.instance;

  static User userFromFirebaseUser({@required FirebaseUser firebaseUser}) {
    if (firebaseUser == null) return null;
    print("Result : ${firebaseUser.displayName} ${firebaseUser.photoUrl} ${firebaseUser.email}");
    return User(
      uid: firebaseUser.uid,
      email: firebaseUser.email,
      name: firebaseUser.displayName,
      imageURL: firebaseUser.photoUrl,
    );
  }


  static Future<User> saveDbUser({@required FirebaseUser firebaseUser}) async {
    User user = userFromFirebaseUser(firebaseUser: firebaseUser);
    Map userMap = user.toMap();

    await firestore.collection("users").document(user.uid).setData(userMap);
    return await getDbUser(user.uid);
  }

  static Future<User> getDbUser(String uid) async {
    DocumentSnapshot documentSnapshot = await Firestore.instance.collection("users").document(uid).get();
    print(User.fromMap(documentSnapshot.data).toString());
    return User.fromMap(documentSnapshot.data);
  }
}

Модель пользователя:

class User {
  final String uid;
  String email;
  String userName;
  String name;
  String imageURL;
  int level;
  DateTime createdAt;
  DateTime updatedAt;

  User({
    @required this.uid,
    @required this.email,
    this.userName,
    this.name,
    this.imageURL,
    this.level,
    this.createdAt,
    this.updatedAt,
  });

  User.fromMap(Map<String, dynamic> map)
      : this.uid = map["uid"],
        this.email = map["email"],
        this.userName = map["userName"],
        this.name = map["name"],
        this.imageURL = map["imageURL"],
        this.level = int.parse(map["level"]),
        this.createdAt = (map["createdAt"] as Timestamp).toDate(),
        this.updatedAt = (map["updatedAt"] as Timestamp).toDate();

  Map<String, dynamic> toMap() {
    DateTime now = DateTime.now().toLocal().toUtc();
    return {
      'uid': this.uid,
      'email': this.email,
      'userName': this.userName ?? this.email.substring(0, this.email.indexOf("@")) + Random().nextInt(1000).toString(),
      'name': this.name,
      'imageURL': this.imageURL ?? "https://www.logolynx.com/images/logolynx/61/61ba01858af7f2ea1184238e9f2771f2.png",
      'level': this.level ?? 1,
      'createdAt': this.createdAt ?? now,
      'updatedAt': this.updatedAt ?? now,
    };
  }
}