使用FLUTTER和FIREBASE时出现此错误：类型'User'不是类型'String'的子类型

Question

我正在关注以下视频：

https://www.youtube.com/watch?v=LlzC0X4oCrc&list=PLxefhmF0pcPkC__GnBhBmGl4013eBYLWh&index=14

编译器消息：

lib/pages/HomePage.dart:129:38: Error: The argument type 'User' can't be assigned to the parameter type 'String'.
 - 'User' is from 'package:buddiesgram/models/user.dart' ('lib/models/user.dart').
          ProfilePage(userProfileId: currentUser),

HomePage.dart

Scaffold buildHomeScreen() {
    return Scaffold(
      body: PageView(
        children: <Widget>[
          //TimeLinePage(),
          RaisedButton.icon(onPressed: logoutUser, icon: Icon(Icons.close), label: Text("Sign Out")),
          SearchPage(),
          UploadPage(gCurrentUser: currentUser,), 
          NotificationsPage(),
          ProfilePage(userProfileId: currentUser), /// --- esto me da error......
        ],
        controller: pageController,
        onPageChanged: whenPageChanges,
        physics: NeverScrollableScrollPhysics(),
      ),

ProfilePage.dart

class ProfilePage extends StatefulWidget{
  final String userProfileId;
  ProfilePage({this.userProfileId});

  @override
  _ProfilePageState createState() => _ProfilePageState();
}

class  _ProfilePageState extends State<ProfilePage>{
  final String currentOnlineUserId = currentUser?.id;

  createProfileTopView(){
    return FutureBuilder(
        future: usersReference.document(widget.userProfileId).get(),

user.dart

class User {
  final String id;
  final String profileName;
  final String username;
  final String url;
  final String email;
  final String bio;

  User({
    this.id,
    this.profileName,
    this.username,
    this.url,
    this.email,
    this.bio,
  });

  factory User.fromDocument(DocumentSnapshot doc) {
    return User(
      id: doc.documentID,
      email: doc['email'],
      username: doc['username'],
      url: doc['url'],
      profileName: doc['profileName'],
      bio: doc['bio'],
    );
  }
}