Firebase Exception building a Consumer<UserManager> // [core/no-app] No Firebase App '[DEFAULT]' has been created - call Firebase.initializeApp()

Question

I'm caught up in the middle of this error, and I can't even begin to think of a way to fix it. I tryed in many ways to put up the Firebase.initializeApp(); into my code, but I didn't manage to do it the right way. I already have the packages in my pubspec.yaml, including Firebase Core, Auth, Cloud Firestore... I believe that my user manager is correct, but do I have to call the firebase initialize in it? I put the initialize Firebase on my main, just like this:

Future<void> main() async {
  runApp(MyApp());
  Firebase.initializeApp();
}

This was the exception:

════════ Exception caught by widgets library ═══════════════════════════════════════════════════════
The following FirebaseException was thrown building Consumer<UserManager>(dirty, dependencies: [_InheritedProviderScope<UserManager>]):
[core/no-app] No Firebase App '[DEFAULT]' has been created - call Firebase.initializeApp()

The relevant error-causing widget was: 
  Consumer<UserManager> file:///C:/Users/adrie/Documents/renata_osorio_nails/lib/screens/login/login_screen.dart:40:22
When the exception was thrown, this was the stack: 
#0      MethodChannelFirebase.app (package:firebase_core_platform_interface/src/method_channel/method_channel_firebase.dart:118:5)
#1      Firebase.app (package:firebase_core/src/firebase.dart:52:41)
#2      FirebaseAuth.instance (package:firebase_auth/src/firebase_auth.dart:37:47)
#3      new UserManager (package:renata_osorio_nails/models/user_manager.dart:11:42)
#4      MyApp.build.<anonymous closure> (package:renata_osorio_nails/main.dart:20:22)
...
════════════════════════════════════════════════════════════════════════════════════════════════════

And my code in login screen is as it follows:

import 'package:firebase_core/firebase_core.dart';
import 'package:flutter/material.dart';
import 'package:renata_osorio_nails/helpers/validators.dart';
import 'package:provider/provider.dart';
import 'package:renata_osorio_nails/models/user_manager.dart';
import 'package:renata_osorio_nails/models/user.dart';

class LoginScreen extends StatelessWidget {

  final TextEditingController emailController = TextEditingController();
  final TextEditingController passController = TextEditingController();
//Controladores de texto

  final GlobalKey<FormState> formKey = GlobalKey<FormState>();
  //Chave de formulário
  final GlobalKey<ScaffoldState> scaffoldKey = GlobalKey<ScaffoldState>();
//Chave Snackbar

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      key: scaffoldKey,
      appBar: AppBar(
        title: const Text('Entrar'),
        centerTitle: true,
        actions: [FlatButton(
          onPressed: (){
            Navigator.of(context).pushReplacementNamed('/signup');
          },
          textColor: Colors.white,
          child: const Text('CRIAR CONTA',
          style: TextStyle(fontSize: 14),),
        )],
      ),
      body: Center(
        child: Card(
            margin: const EdgeInsets.symmetric(horizontal: 16),
            child: Form(
              key: formKey,
              child: Consumer<UserManager>(
                builder: (_, userManager, child){
                  return ListView(
                    padding: const EdgeInsets.all(16),
                    shrinkWrap: true,
                    children: [
                      TextFormField(
                        controller: emailController,
                        enabled: !userManager.loading,
                        decoration: const InputDecoration(hintText: 'E-mail'),
                        keyboardType: TextInputType.emailAddress,
                        autocorrect: false,
                        validator: (email) {
                          if(!emailValid(email))
                            return 'E-mail inválido';
                          return null;
                        },
                      ),
                      const SizedBox(
                        height: 16,
                      ),
                      TextFormField(
                        controller: passController,
                        enabled: !userManager.loading,
                        decoration: const InputDecoration(hintText: 'Senha'),
                        autocorrect: false,
                        obscureText: true,
                        validator: (pass) {
                          if (pass.isEmpty || pass.length < 8)
                            return 'Senha inválida';
                          return null;
                        },
                      ),
                      Align(
                        alignment: Alignment.centerRight,
                        child: FlatButton(
                          onPressed: () {},
                          padding: EdgeInsets.zero,
                          child: const Text('Esqueci minha senha'),
                        ),
                      ),
                      const SizedBox(
                        height: 16,
                      ),
                      SizedBox(
                        height: 44,
                        child: RaisedButton(
                          onPressed: userManager.loading ? null : () {
                            if(formKey.currentState.validate()){
                              context.read()<UserManager>().signIn(
                                  user: AppUser(
                                    email: emailController.text,
                                    password: passController.text,
                                  ),
                                  onFail: (e){
                                    scaffoldKey.currentState.showSnackBar(
                                        SnackBar(
                                          content: Text ('Falha ao entrar: $e'),
                                          backgroundColor: Colors.red,
                                        )
                                    );
                                  },
                                  onSuccess: (){
                                    //TODO: Fechar a tela de login
                                  }
                              );}},
                          color: Theme.of(context).primaryColor,
                          disabledColor: Theme.of(context).primaryColor.
                              withAlpha(100),
                          textColor: Colors.white,
                          child: userManager.loading ?
                          CircularProgressIndicator(
                            valueColor: AlwaysStoppedAnimation(Colors.white),
                          ) :
                          const Text(
                            'Entrar',
                            style: TextStyle(fontSize: 18),
                          ),
                        ),
                      ),
                    ],
                  );
                },
              ),
            )),
      ),
    );
  }
}

How can I fix this?

Answer 1

Have you checked if the line is executed? If it isn't, try putting the line before the runApp() call or in the initState() method of your widget.