How do I fix this flutter/firebase authentication problem?

I get the error: The argument type 'MyUser? Function(User?, String)' can't be assigned to the parameter type 'MyUser? Function(User?)'

Auth.dart: RED LINE are under "_userFromFirebaseUser"

import 'package:firebase_auth/firebase_auth.dart'; import 'package:hyttekos/models/user.dart'; class AuthService { final FirebaseAuth _auth = FirebaseAuth.instance; //MyUser Function(User? event, String name)? get userFromFirebaseUser => null; // create user obj MyUser? _userFromFirebaseUser(User? user, String name) { // ignore: unnecessary_null_comparison return user != null ? MyUser(uid: user.uid, groupId: '', name: name) : null; } // auth change user stream Stream<MyUser?> get user { return _auth.authStateChanges().map(_userFromFirebaseUser); **RED LINE are under "_userFromFirebaseUser"** } // sign in anon Future signInAnon(String username) async { try { UserCredential userCredidential = await _auth.signInAnonymously(); User? user = userCredidential.user; return _userFromFirebaseUser(user!, username); } catch (e) { // ignore: avoid_print print(e.toString()); return null; } } } 

User.dart:

class MyUser { final String uid; final String name; String groupId; MyUser({ required this.uid, required this.name, required this.groupId, }); }