空安全问题？

[YuQi9797]

flutter_in_action_source_code/github_client_app/lib/states/profile_change_notifier.dart

Line 14 in e5e54b3

User get user => _profile.user;

大佬您好，关于此处: User get user => _profile.user;
由于_profile.user 是 User? 类型的， 所以在get的返回类型中改为了 User?
但当改好后User? get user => _profile.user; 又出现问题提示：The return type of getter 'user' is 'User?' which isn't a subtype of the type 'User' of its setter 'user'.

请问这种该如何解决呢？ 谢谢！

[YuQi9797]

这样吗？

class UserModel extends ProfileChangeNotifier {
  User? get user => _profile.user;

  // APP是否登录（如果有用户信息，则证明登录过）
  bool get isLogin => user != null;

  // 用户信息发生变化，更新用户信息并通知依赖它的子孙Widgets更新
  set user(User? user) {
    if (user?.login != _profile.user?.login) {
      _profile.lastLogin = _profile.user?.login;
      _profile.user = user;
      notifyListeners();
    }
  }
}

[liwei118]

Is the problem solved?
I changed the judgment that controls security, but there are new problems in my code.

error: The return type of getter 'user' is 'User?' which isn't a subtype of the type 'User' of its setter 'user'.

class UserModel extends ProfileChangeNotifier {
  User? get user => _profile.user;

  // APP是否登录(如果有用户信息，则证明登录过)
  bool get isLogin => user != null;

  //用户信息发生变化，更新用户信息并通知依赖它的子孙Widgets更新
  set user(User user) {
    if (user?.login != _profile.user?.login) {
      _profile.lastLogin = _profile.user?.login;
      _profile.user = user;
      notifyListeners();
    }
  }
}