keep getting "Null check operator used on a null value" error. i've checked my code 100 times - flutter

Question

keep getting "Null check operator used on a null value" error
actually im trying to use providers to get values from database and use em in my app
but im stuck at this i checked my code in every single way but still i keep getting this error
:lib\providers\user_provider.dart
import 'package:flutter/widgets.dart';
import 'package:test_app/models/user.dart';
import 'package:test_app/resources/auth_methods.dart';
class UserProvider with ChangeNotifier {
User? _user;
final AuthMethods _authMethods = AuthMethods();
User get getUser => _user!;
Future<void> refreshUser() async {
User user = await _authMethods.getUserDetails();
_user = user;
notifyListeners();
}
}
lib\pages\home.dart
import 'package:cloud_firestore/cloud_firestore.dart';
import 'package:firebase_auth/firebase_auth.dart';
import 'package:flutter/material.dart';
import 'package:provider/provider.dart';
import 'package:test_app/providers/user_provider.dart';
import 'package:test_app/models/user.dart' as model;
// import 'dart:html';
class Home extends StatefulWidget {
const Home({Key? key}) : super(key: key);
#override
State<Home> createState() => _HomeState();
}
class _HomeState extends State<Home> {
#override
void initState() {
super.initState();
addData();
}
addData() async {
UserProvider _userProvider =
Provider.of<UserProvider>(context, listen: false);
await _userProvider.refreshUser();
}
#override
Widget build(BuildContext context) {
model.User user = Provider.of<UserProvider>(context).getUser;
return Scaffold(
body: Center(
child: Text("this is homepage"),
),
);
}
}
debug snippet
══╡ EXCEPTION CAUGHT BY WIDGETS LIBRARY ╞═══════════════════════════════════════════════════════════
The following _CastError was thrown building Home(dirty, dependencies:
[_InheritedProviderScope<UserProvider?>], state: _HomeState#17895):
Null check operator used on a null value
The relevant error-causing widget was:
Home Home:file:///C:/Users/abc/Desktop/flutter/test_app/lib/main.dart:53:34
When the exception was thrown, this was the stack:
#0 UserProvider.getUser (package:test_app/providers/user_provider.dart:9:28)
#1 _HomeState.build (package:test_app/pages/home.dart:36:59)
#2 StatefulElement.build (package:flutter/src/widgets/framework.dart:4870:27)
#3 ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:4754:15)
#4 StatefulElement.performRebuild (package:flutter/src/widgets/framework.dart:4928:11)
#5 Element.rebuild (package:flutter/src/widgets/framework.dart:4477:5)
#6 ComponentElement._firstBuild (package:flutter/src/widgets/framework.dart:4735:5)
#7 StatefulElement._firstBuild (package:flutter/src/widgets/framework.dart:4919:11)
#8 ComponentElement.mount (package:flutter/src/widgets/framework.dart:4729:5)
#9 Element.inflateWidget (package:flutter/src/widgets/framework.dart:3790:14)
#10 Element.updateChild (package:flutter/src/widgets/framework.dart:3524:20)
#11 ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:4780:16)
#12 StatefulElement.performRebuild (package:flutter/src/widgets/framework.dart:4928:11)
#13 Element.rebuild (package:flutter/src/widgets/framework.dart:4477:5)
#14 BuildOwner.buildScope (package:flutter/src/widgets/framework.dart:2659:19)
#15 WidgetsBinding.drawFrame (package:flutter/src/widgets/binding.dart:882:21)
#16 RendererBinding._handlePersistentFrameCallback (package:flutter/src/rendering/binding.dart:363:5)
#17 SchedulerBinding._invokeFrameCallback (package:flutter/src/scheduler/binding.dart:1144:15)
#18 SchedulerBinding.handleDrawFrame (package:flutter/src/scheduler/binding.dart:1081:9)
#19 SchedulerBinding.scheduleWarmUpFrame.<anonymous closure> (package:flutter/src/scheduler/binding.dart:862:7)
(elided 11 frames from class _RawReceivePortImpl, class _Timer, dart:async, and dart:async-patch)
idk what the problem actually im new to flutter and dart
i've using python for my whole life

Answer 1

refreshUser is a future and it sets _user but because you're calling getUser IMMEDIATELY build method, which basically returns _user as a non-null value, the error would be thrown.
Try this:
class UserProvider with ChangeNotifier {
User? _user;
final AuthMethods _authMethods = AuthMethods();
User? get getUser => _user;
Future<void> refreshUser() async {
User user = await _authMethods.getUserDetails();
_user = user;
notifyListeners();
}
}
And your _HomeState:
class _HomeState extends State<Home> {
#override
void initState() {
super.initState();
addData();
}
addData() async {
UserProvider _userProvider =
Provider.of<UserProvider>(context, listen: false);
await _userProvider.refreshUser();
}
#override
Widget build(BuildContext context) {
model.User? user = Provider.of<UserProvider>(context).getUser;
return Scaffold(
body: Center(
child: Text("this is homepage"),
),
);
}
}

Answer 2

In User_Provider.dart,
instead of doing:
User get getUser => _user!;
Do this:
User? get getUser => _user;