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flutterflutter-provider

Getting a black screen when using provider in Flutter to change layout after logging in

I'm using provider to handle User login in a Flutter app. I created a class called AccountManager that extends ChangeNotifier and updates a boolean that tells my main Scaffold which of two widgets to use to draw its contents.

When the app starts, I'm not logged in and it loads NotLoggedInLayout() properly, which has a form to log in. I enter my credentials, log in using the AccountManager which in turn calls notifyListeners() and tells my Consumer to redraw and change to LoggedInLayout(). I can see that it redraws to the correct screen for a short moment but then a black screen covers everything.

After that, if I press "R" to reload the app, it shows LoggedInLayout() properly because it remembers the login. But if I press "r" to hot reload, I get this error in the terminal:

Performing hot reload...                                               ⢿
══╡ EXCEPTION CAUGHT BY WIDGETS LIBRARY
╞═══════════════════════════════════════════════════════════
The following assertion was thrown building
Navigator-[GlobalObjectKey<NavigatorState>
_WidgetsAppState#1e7c5](dirty, dependencies: [HeroControllerScope,
UnmanagedRestorationScope],
state: NavigatorState#c9fc1(tickers: tracking 0 tickers)):
'package:flutter/src/widgets/navigator.dart': Failed assertion: line 5308 pos 12:
'_history.isNotEmpty': is not true.

Either the assertion indicates an error in the framework itself, or we should
provide substantially
more information in this error message to help you determine and fix the
underlying cause.
In either case, please report this assertion by filing a bug on GitHub:
  https://github.com/flutter/flutter/issues/new?template=2_bug.md

The relevant error-causing widget was:
  MaterialApp file:///home/bruno/Desarrollo/TinviTo/creators/lib/main.dart:20:14

When the exception was thrown, this was the stack:
#2      NavigatorState.build (package:flutter/src/widgets/navigator.dart:5308:12)
#3      StatefulElement.build
(package:flutter/src/widgets/framework.dart:4710:27)
#4      ComponentElement.performRebuild
(package:flutter/src/widgets/framework.dart:4593:15)
#5      StatefulElement.performRebuild
(package:flutter/src/widgets/framework.dart:4766:11)
#6      Element.rebuild (package:flutter/src/widgets/framework.dart:4284:5)
#7      StatefulElement.update
(package:flutter/src/widgets/framework.dart:4798:5)
#8      Element.updateChild (package:flutter/src/widgets/framework.dart:3363:15)
#9      ComponentElement.performRebuild
(package:flutter/src/widgets/framework.dart:4618:16)
#10     Element.rebuild (package:flutter/src/widgets/framework.dart:4284:5)
#11     ProxyElement.update (package:flutter/src/widgets/framework.dart:4945:5)
#12     Element.updateChild (package:flutter/src/widgets/framework.dart:3363:15)
#13     ComponentElement.performRebuild
(package:flutter/src/widgets/framework.dart:4618:16)
#14     Element.rebuild (package:flutter/src/widgets/framework.dart:4284:5)
#15     ProxyElement.update (package:flutter/src/widgets/framework.dart:4945:5)
#16     Element.updateChild (package:flutter/src/widgets/framework.dart:3363:15)
#17     ComponentElement.performRebuild
(package:flutter/src/widgets/framework.dart:4618:16)
#18     Element.rebuild (package:flutter/src/widgets/framework.dart:4284:5)
#19     ProxyElement.update (package:flutter/src/widgets/framework.dart:4945:5)
#20     Element.updateChild (package:flutter/src/widgets/framework.dart:3363:15)
#21     ComponentElement.performRebuild
(package:flutter/src/widgets/framework.dart:4618:16)
#22     Element.rebuild (package:flutter/src/widgets/framework.dart:4284:5)
#23     StatelessElement.update
(package:flutter/src/widgets/framework.dart:4674:5)
#24     Element.updateChild (package:flutter/src/widgets/framework.dart:3363:15)
#25     ComponentElement.performRebuild
(package:flutter/src/widgets/framework.dart:4618:16)
#26     Element.rebuild (package:flutter/src/widgets/framework.dart:4284:5)
#27     ProxyElement.update (package:flutter/src/widgets/framework.dart:4945:5)
#28     Element.updateChild (package:flutter/src/widgets/framework.dart:3363:15)
#29     ComponentElement.performRebuild
(package:flutter/src/widgets/framework.dart:4618:16)
#30     Element.rebuild (package:flutter/src/widgets/framework.dart:4284:5)
#31     StatelessElement.update
(package:flutter/src/widgets/framework.dart:4674:5)
#32     Element.updateChild (package:flutter/src/widgets/framework.dart:3363:15)
#33     ComponentElement.performRebuild
(package:flutter/src/widgets/framework.dart:4618:16)
#34     StatefulElement.performRebuild
(package:flutter/src/widgets/framework.dart:4766:11)
#35     Element.rebuild (package:flutter/src/widgets/framework.dart:4284:5)
#36     StatefulElement.update
(package:flutter/src/widgets/framework.dart:4798:5)
#37     Element.updateChild (package:flutter/src/widgets/framework.dart:3363:15)
#38     ComponentElement.performRebuild
(package:flutter/src/widgets/framework.dart:4618:16)
#39     Element.rebuild (package:flutter/src/widgets/framework.dart:4284:5)
#40     ProxyElement.update (package:flutter/src/widgets/framework.dart:4945:5)
#41     Element.updateChild (package:flutter/src/widgets/framework.dart:3363:15)
#42     ComponentElement.performRebuild
(package:flutter/src/widgets/framework.dart:4618:16)
#43     StatefulElement.performRebuild
(package:flutter/src/widgets/framework.dart:4766:11)
#44     Element.rebuild (package:flutter/src/widgets/framework.dart:4284:5)
#45     StatefulElement.update
(package:flutter/src/widgets/framework.dart:4798:5)
#46     Element.updateChild (package:flutter/src/widgets/framework.dart:3363:15)
#47     ComponentElement.performRebuild
(package:flutter/src/widgets/framework.dart:4618:16)
#48     Element.rebuild (package:flutter/src/widgets/framework.dart:4284:5)
#49     StatelessElement.update
(package:flutter/src/widgets/framework.dart:4674:5)
#50     Element.updateChild (package:flutter/src/widgets/framework.dart:3363:15)
#51     ComponentElement.performRebuild
(package:flutter/src/widgets/framework.dart:4618:16)
#52     Element.rebuild (package:flutter/src/widgets/framework.dart:4284:5)
#53     ProxyElement.update (package:flutter/src/widgets/framework.dart:4945:5)
#54     Element.updateChild (package:flutter/src/widgets/framework.dart:3363:15)
#55     ComponentElement.performRebuild
(package:flutter/src/widgets/framework.dart:4618:16)
#56     Element.rebuild (package:flutter/src/widgets/framework.dart:4284:5)
#57     StatelessElement.update
(package:flutter/src/widgets/framework.dart:4674:5)
#58     Element.updateChild (package:flutter/src/widgets/framework.dart:3363:15)
#59     ComponentElement.performRebuild
(package:flutter/src/widgets/framework.dart:4618:16)
#60     Element.rebuild (package:flutter/src/widgets/framework.dart:4284:5)
#61     ProxyElement.update (package:flutter/src/widgets/framework.dart:4945:5)
#62     Element.updateChild (package:flutter/src/widgets/framework.dart:3363:15)
#63     ComponentElement.performRebuild
(package:flutter/src/widgets/framework.dart:4618:16)
#64     Element.rebuild (package:flutter/src/widgets/framework.dart:4284:5)
#65     ProxyElement.update (package:flutter/src/widgets/framework.dart:4945:5)
#66     Element.updateChild (package:flutter/src/widgets/framework.dart:3363:15)
#67     SingleChildRenderObjectElement.update
(package:flutter/src/widgets/framework.dart:6114:14)
#68     Element.updateChild (package:flutter/src/widgets/framework.dart:3363:15)
#69     ComponentElement.performRebuild
(package:flutter/src/widgets/framework.dart:4618:16)
#70     StatefulElement.performRebuild
(package:flutter/src/widgets/framework.dart:4766:11)
#71     Element.rebuild (package:flutter/src/widgets/framework.dart:4284:5)
#72     StatefulElement.update
(package:flutter/src/widgets/framework.dart:4798:5)
#73     Element.updateChild (package:flutter/src/widgets/framework.dart:3363:15)
#74     ComponentElement.performRebuild
(package:flutter/src/widgets/framework.dart:4618:16)
#75     Element.rebuild (package:flutter/src/widgets/framework.dart:4284:5)
#76     ProxyElement.update (package:flutter/src/widgets/framework.dart:4945:5)
#77     Element.updateChild (package:flutter/src/widgets/framework.dart:3363:15)
#78     ComponentElement.performRebuild
(package:flutter/src/widgets/framework.dart:4618:16)
#79     StatefulElement.performRebuild
(package:flutter/src/widgets/framework.dart:4766:11)
#80     Element.rebuild (package:flutter/src/widgets/framework.dart:4284:5)
#81     StatefulElement.update
(package:flutter/src/widgets/framework.dart:4798:5)
#82     Element.updateChild (package:flutter/src/widgets/framework.dart:3363:15)
#83     ComponentElement.performRebuild
(package:flutter/src/widgets/framework.dart:4618:16)
#84     Element.rebuild (package:flutter/src/widgets/framework.dart:4284:5)
#85     ProxyElement.update (package:flutter/src/widgets/framework.dart:4945:5)
#86     _InheritedNotifierElement.update
(package:flutter/src/widgets/inherited_notifier.dart:181:11)
#87     Element.updateChild (package:flutter/src/widgets/framework.dart:3363:15)
#88     ComponentElement.performRebuild
(package:flutter/src/widgets/framework.dart:4618:16)
#89     StatefulElement.performRebuild
(package:flutter/src/widgets/framework.dart:4766:11)
#90     Element.rebuild (package:flutter/src/widgets/framework.dart:4284:5)
#91     StatefulElement.update
(package:flutter/src/widgets/framework.dart:4798:5)
#92     Element.updateChild (package:flutter/src/widgets/framework.dart:3363:15)
#93     ComponentElement.performRebuild
(package:flutter/src/widgets/framework.dart:4618:16)
#94     Element.rebuild (package:flutter/src/widgets/framework.dart:4284:5)
#95     ProxyElement.update (package:flutter/src/widgets/framework.dart:4945:5)
#96     Element.updateChild (package:flutter/src/widgets/framework.dart:3363:15)
#97     ComponentElement.performRebuild
(package:flutter/src/widgets/framework.dart:4618:16)
#98     StatefulElement.performRebuild
(package:flutter/src/widgets/framework.dart:4766:11)
#99     Element.rebuild (package:flutter/src/widgets/framework.dart:4284:5)
#100    StatefulElement.update
(package:flutter/src/widgets/framework.dart:4798:5)
#101    Element.updateChild (package:flutter/src/widgets/framework.dart:3363:15)
#102    ComponentElement.performRebuild
(package:flutter/src/widgets/framework.dart:4618:16)
#103    Element.rebuild (package:flutter/src/widgets/framework.dart:4284:5)
#104    ProxyElement.update (package:flutter/src/widgets/framework.dart:4945:5)
#105    Element.updateChild (package:flutter/src/widgets/framework.dart:3363:15)
#106    ComponentElement.performRebuild
(package:flutter/src/widgets/framework.dart:4618:16)
#107    StatefulElement.performRebuild
(package:flutter/src/widgets/framework.dart:4766:11)
#108    Element.rebuild (package:flutter/src/widgets/framework.dart:4284:5)
#109    StatefulElement.update
(package:flutter/src/widgets/framework.dart:4798:5)
#110    Element.updateChild (package:flutter/src/widgets/framework.dart:3363:15)
#111    ComponentElement.performRebuild
(package:flutter/src/widgets/framework.dart:4618:16)
#112    Element.rebuild (package:flutter/src/widgets/framework.dart:4284:5)
#113    ProxyElement.update (package:flutter/src/widgets/framework.dart:4945:5)
#114    Element.updateChild (package:flutter/src/widgets/framework.dart:3363:15)
#115    ComponentElement.performRebuild
(package:flutter/src/widgets/framework.dart:4618:16)
#116    StatefulElement.performRebuild
(package:flutter/src/widgets/framework.dart:4766:11)
#117    Element.rebuild (package:flutter/src/widgets/framework.dart:4284:5)
#118    StatefulElement.update
(package:flutter/src/widgets/framework.dart:4798:5)
#119    Element.updateChild (package:flutter/src/widgets/framework.dart:3363:15)
#120    ComponentElement.performRebuild
(package:flutter/src/widgets/framework.dart:4618:16)
#121    Element.rebuild (package:flutter/src/widgets/framework.dart:4284:5)
#122    ProxyElement.update (package:flutter/src/widgets/framework.dart:4945:5)
#123    _InheritedNotifierElement.update
(package:flutter/src/widgets/inherited_notifier.dart:181:11)
#124    Element.updateChild (package:flutter/src/widgets/framework.dart:3363:15)
#125    SingleChildRenderObjectElement.update
(package:flutter/src/widgets/framework.dart:6114:14)
#126    Element.updateChild (package:flutter/src/widgets/framework.dart:3363:15)
#127    ComponentElement.performRebuild
(package:flutter/src/widgets/framework.dart:4618:16)
#128    Element.rebuild (package:flutter/src/widgets/framework.dart:4284:5)
#129    ProxyElement.update (package:flutter/src/widgets/framework.dart:4945:5)
#130    _InheritedNotifierElement.update
(package:flutter/src/widgets/inherited_notifier.dart:181:11)
#131    Element.updateChild (package:flutter/src/widgets/framework.dart:3363:15)
#132    ComponentElement.performRebuild
(package:flutter/src/widgets/framework.dart:4618:16)
#133    StatefulElement.performRebuild
(package:flutter/src/widgets/framework.dart:4766:11)
#134    Element.rebuild (package:flutter/src/widgets/framework.dart:4284:5)
#135    StatefulElement.update
(package:flutter/src/widgets/framework.dart:4798:5)
#136    Element.updateChild (package:flutter/src/widgets/framework.dart:3363:15)
#137    ComponentElement.performRebuild
(package:flutter/src/widgets/framework.dart:4618:16)
#138    StatefulElement.performRebuild
(package:flutter/src/widgets/framework.dart:4766:11)
#139    Element.rebuild (package:flutter/src/widgets/framework.dart:4284:5)
#140    StatefulElement.update
(package:flutter/src/widgets/framework.dart:4798:5)
#141    Element.updateChild (package:flutter/src/widgets/framework.dart:3363:15)
#142    ComponentElement.performRebuild
(package:flutter/src/widgets/framework.dart:4618:16)
#143    Element.rebuild (package:flutter/src/widgets/framework.dart:4284:5)
#144    ProxyElement.update (package:flutter/src/widgets/framework.dart:4945:5)
#145    _InheritedNotifierElement.update
(package:flutter/src/widgets/inherited_notifier.dart:181:11)
#146    Element.updateChild (package:flutter/src/widgets/framework.dart:3363:15)
#147    SingleChildRenderObjectElement.update
(package:flutter/src/widgets/framework.dart:6114:14)
#148    Element.updateChild (package:flutter/src/widgets/framework.dart:3363:15)
#149    ComponentElement.performRebuild
(package:flutter/src/widgets/framework.dart:4618:16)
#150    Element.rebuild (package:flutter/src/widgets/framework.dart:4284:5)
#151    ProxyElement.update (package:flutter/src/widgets/framework.dart:4945:5)
#152    _InheritedNotifierElement.update
(package:flutter/src/widgets/inherited_notifier.dart:181:11)
#153    Element.updateChild (package:flutter/src/widgets/framework.dart:3363:15)
#154    ComponentElement.performRebuild
(package:flutter/src/widgets/framework.dart:4618:16)
#155    StatefulElement.performRebuild
(package:flutter/src/widgets/framework.dart:4766:11)
#156    Element.rebuild (package:flutter/src/widgets/framework.dart:4284:5)
#157    StatefulElement.update
(package:flutter/src/widgets/framework.dart:4798:5)
#158    Element.updateChild (package:flutter/src/widgets/framework.dart:3363:15)
#159    ComponentElement.performRebuild
(package:flutter/src/widgets/framework.dart:4618:16)
#160    StatefulElement.performRebuild
(package:flutter/src/widgets/framework.dart:4766:11)
#161    Element.rebuild (package:flutter/src/widgets/framework.dart:4284:5)
#162    StatefulElement.update
(package:flutter/src/widgets/framework.dart:4798:5)
#163    Element.updateChild (package:flutter/src/widgets/framework.dart:3363:15)
#164    ComponentElement.performRebuild
(package:flutter/src/widgets/framework.dart:4618:16)
#165    Element.rebuild (package:flutter/src/widgets/framework.dart:4284:5)
#166    ProxyElement.update (package:flutter/src/widgets/framework.dart:4945:5)
#167    Element.updateChild (package:flutter/src/widgets/framework.dart:3363:15)
#168    ComponentElement.performRebuild
(package:flutter/src/widgets/framework.dart:4618:16)
#169    StatefulElement.performRebuild
(package:flutter/src/widgets/framework.dart:4766:11)
#170    Element.rebuild (package:flutter/src/widgets/framework.dart:4284:5)
#171    StatefulElement.update
(package:flutter/src/widgets/framework.dart:4798:5)
#172    Element.updateChild (package:flutter/src/widgets/framework.dart:3363:15)
#173    ComponentElement.performRebuild
(package:flutter/src/widgets/framework.dart:4618:16)
#174    Element.rebuild (package:flutter/src/widgets/framework.dart:4284:5)
#175    ProxyElement.update (package:flutter/src/widgets/framework.dart:4945:5)
#176    Element.updateChild (package:flutter/src/widgets/framework.dart:3363:15)
#177    ComponentElement.performRebuild
(package:flutter/src/widgets/framework.dart:4618:16)
#178    StatefulElement.performRebuild
(package:flutter/src/widgets/framework.dart:4766:11)
#179    Element.rebuild (package:flutter/src/widgets/framework.dart:4284:5)
#180    StatefulElement.update
(package:flutter/src/widgets/framework.dart:4798:5)
#181    Element.updateChild (package:flutter/src/widgets/framework.dart:3363:15)
#182    ComponentElement.performRebuild
(package:flutter/src/widgets/framework.dart:4618:16)
#183    StatefulElement.performRebuild
(package:flutter/src/widgets/framework.dart:4766:11)
#184    Element.rebuild (package:flutter/src/widgets/framework.dart:4284:5)
#185    StatefulElement.update
(package:flutter/src/widgets/framework.dart:4798:5)
#186    Element.updateChild (package:flutter/src/widgets/framework.dart:3363:15)
#187    ComponentElement.performRebuild
(package:flutter/src/widgets/framework.dart:4618:16)
#188    Element.rebuild (package:flutter/src/widgets/framework.dart:4284:5)
#189    ProxyElement.update (package:flutter/src/widgets/framework.dart:4945:5)
#190    Element.updateChild (package:flutter/src/widgets/framework.dart:3363:15)
#191    ComponentElement.performRebuild
(package:flutter/src/widgets/framework.dart:4618:16)
#192    Element.rebuild (package:flutter/src/widgets/framework.dart:4284:5)
#193    ProxyElement.update (package:flutter/src/widgets/framework.dart:4945:5)
#194    Element.updateChild (package:flutter/src/widgets/framework.dart:3363:15)
#195    ComponentElement.performRebuild
(package:flutter/src/widgets/framework.dart:4618:16)
#196    StatefulElement.performRebuild
(package:flutter/src/widgets/framework.dart:4766:11)
#197    Element.rebuild (package:flutter/src/widgets/framework.dart:4284:5)
#198    StatefulElement.update
(package:flutter/src/widgets/framework.dart:4798:5)
#199    Element.updateChild (package:flutter/src/widgets/framework.dart:3363:15)
#200    ComponentElement.performRebuild
(package:flutter/src/widgets/framework.dart:4618:16)
#201    _InheritedProviderScopeElement.performRebuild
(package:provider/src/inherited_provider.dart:456:11)
#202    Element.rebuild (package:flutter/src/widgets/framework.dart:4284:5)
#203    ProxyElement.update (package:flutter/src/widgets/framework.dart:4945:5)
#204    _InheritedProviderScopeElement.update
(package:provider/src/inherited_provider.dart:477:11)
#205    Element.updateChild (package:flutter/src/widgets/framework.dart:3363:15)
#206    ComponentElement.performRebuild
(package:flutter/src/widgets/framework.dart:4618:16)
#207    Element.rebuild (package:flutter/src/widgets/framework.dart:4284:5)
#208    StatelessElement.update
(package:flutter/src/widgets/framework.dart:4674:5)
#209    Element.updateChild (package:flutter/src/widgets/framework.dart:3363:15)
#210    ComponentElement.performRebuild
(package:flutter/src/widgets/framework.dart:4618:16)
#211    Element.rebuild (package:flutter/src/widgets/framework.dart:4284:5)
#212    StatelessElement.update
(package:flutter/src/widgets/framework.dart:4674:5)
#213    Element.updateChild (package:flutter/src/widgets/framework.dart:3363:15)
#214    ComponentElement.performRebuild
(package:flutter/src/widgets/framework.dart:4618:16)
#215    Element.rebuild (package:flutter/src/widgets/framework.dart:4284:5)
#216    StatelessElement.update
(package:flutter/src/widgets/framework.dart:4674:5)
#217    Element.updateChild (package:flutter/src/widgets/framework.dart:3363:15)
#218    ComponentElement.performRebuild
(package:flutter/src/widgets/framework.dart:4618:16)
#219    Element.rebuild (package:flutter/src/widgets/framework.dart:4284:5)
#220    BuildOwner.buildScope
(package:flutter/src/widgets/framework.dart:2582:33)
#221    WidgetsBinding.drawFrame
(package:flutter/src/widgets/binding.dart:875:21)
#222    RendererBinding._handlePersistentFrameCallback
(package:flutter/src/rendering/binding.dart:328:5)
#223    SchedulerBinding._invokeFrameCallback
(package:flutter/src/scheduler/binding.dart:1144:15)
#224    SchedulerBinding.handleDrawFrame
(package:flutter/src/scheduler/binding.dart:1082:9)
#225    SchedulerBinding.scheduleWarmUpFrame.<anonymous closure>
(package:flutter/src/scheduler/binding.dart:865:7)
(elided 6 frames from class _AssertionError, class _RawReceivePortImpl, class
_Timer, and dart:async-patch)

It seems like my provider somehow its messing with the Navigator, but I can't seem to find the cause.

This is my main code:

import 'package:creators/layouts/LoggedIn.dart';
import 'package:creators/layouts/NotLoggedIn.dart';
import 'package:creators/providers/AccountManager.dart';
import 'package:flutter/material.dart';
import 'package:provider/provider.dart';

void main() {
  runApp(MyApp());
}

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MultiProvider(
      providers: [
        ChangeNotifierProvider<AccountManager>(
          create: (_) => AccountManager(),
        ),
      ],
      child: MaterialApp(
        title: 'App Title',
        theme: ThemeData(
          primarySwatch: Colors.blue,
        ),
        home: MyHomePage(
          title: 'App Title',
        ),
        debugShowCheckedModeBanner: false,
      ),
    );
  }
}

class MyHomePage extends StatefulWidget {
  MyHomePage({Key? key, required this.title}) : super(key: key);

  final String title;

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

class _MyHomePageState extends State<MyHomePage> {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text(widget.title),
      ),
      body: Consumer<AccountManager>(
        builder: (context, manager, child) {
          bool isLoggedIn = manager.isLoggedIn;
          return (isLoggedIn) ? LoggedInLayout() : NotLoggedInLayout();
        },
      ),
    );
  }
}

And this is the AccountManager class:

import 'dart:convert';
import 'package:creators/models/User.dart';
import 'package:creators/services/AccountService.dart';
import 'package:flutter/foundation.dart';
import 'package:shared_preferences/shared_preferences.dart';

class AccountManager with ChangeNotifier {
  User? _user;

  User? get user => _user;
  bool get isLoggedIn => _user != null;

  AccountManager() {
    // Inicializar variables desde la base de datos
    _initData();
  }

  void _initData() async {
    await this.loadUser();
    notifyListeners();
  }

  Future localLogin({
    required String email,
    required String password,
  }) async {
    var result = await AccountService.localLogin(
      email: email,
      password: password,
    );
    if (result.statusCode == 200) {
      String sBody = result.body;
      Map<String, dynamic> body = jsonDecode(sBody);
      User user = new User(
        body['name'],
        body['email'],
        body['role'],
        body['token'],
      );
      _user = user;
      await this.saveUser();
      notifyListeners();
    } else {
      String error = jsonDecode(result.body)['message'] ?? 'Error desconocido.';
      throw Exception(error);
    }
  }

  Future localRegister({
    required String name,
    required String email,
    required String password,
  }) async {
    var result = await AccountService.localRegister(
      name: name,
      email: email,
      password: password,
    );
    if (result.statusCode == 200) {
      String sBody = result.body;
      Map<String, dynamic> body = jsonDecode(sBody);
      User user = new User(
        body['name'],
        body['email'],
        body['role'],
        body['token'],
      );
      _user = user;
      await this.saveUser();
      notifyListeners();
    } else {
      String error = jsonDecode(result.body)['message'] ?? 'Error desconocido.';
      throw Exception(error);
    }
  }

  saveUser() async {
    if (_user != null) {
      String bodySerialized = jsonEncode(_user!.toJson());
      SharedPreferences prefs = await SharedPreferences.getInstance();
      prefs.setString('user', bodySerialized);
    }
  }

  loadUser() async {
    SharedPreferences prefs = await SharedPreferences.getInstance();
    String? sBody = prefs.getString('user');
    if (sBody != null) {
      Map<String, dynamic> body = jsonDecode(sBody);
      User user = new User(
        body['name'],
        body['email'],
        body['role'],
        body['token'],
      );
      _user = user;
    }
  }

  void deleteUser() async {
    SharedPreferences prefs = await SharedPreferences.getInstance();
    prefs.remove('user');
  }

  void logout() {
    _user = null;
    this.deleteUser();
    notifyListeners();
  }
}

When I restart the app and it's logged in (showing LoggedInLayout()) I can press the logout button and it properly changes to NotLoggedInLayout() without the black screen. So it seems like the error only happens when I log in and not when I log out.

Solution

  • It's embarassing, but I found out what was happening. It was because I was popping the screen from the Navigator after logging in. I copied the form from another project of mine that didn't change the screen using provider and used Navigator.pop() instead. So my code looked like this:

    await accountManager.localLogin(
  email: email,
  password: password,
);
Navigator.pop(context);

    Since now I changed the layout using Provider and Consumer, the Navigator.pop() was not needed anymore. It was popping my first Scaffold, thus the black screen. The solution was to remove the Navigator.pop(context) line.