Flutter: No Firebase App '[DEFAULT]' has been created - call Firebase.initializeApp()

[dashanan13]

Steps to Reproduce

I am trying to create a separate Authentication class that has various types of authentications as functions like signInAnonymously() and onAuthStateChanged(). The aim is to manage them in one place and use them via providers, there are no UI components in this class and it is purely a Dart class. Unfortunately every compile results in same error: No Firebase App '[DEFAULT]' has been created - call Firebase.initializeApp(). I have tried to initialize it in a constructor, assign it to a variable outside the constructor, etc but the error won't go away and I can not use _firebaseAuth. Please help, this is frustrating.

Expected results:
Clear compilation and application rendering

Actual results:
[core/no-app] No Firebase App '[DEFAULT]' has been created - call Firebase.initializeApp()

Sample GitHub project hosted: https://github.com/dashanan13/time_tracker_flutter_course.git

_I can not get rid of this error no matter to how I arrange Firebase.initializeApp(). Please help_

`
import 'package:firebase_auth/firebase_auth.dart';
import 'package:firebase_core/firebase_core.dart';
import 'package:flutter/foundation.dart';
import 'package:flutter/services.dart';
import 'package:flutter_facebook_login/flutter_facebook_login.dart';
import 'package:google_sign_in/google_sign_in.dart';

class MyUser {
  MyUser({@required this.uid});
  final String uid;
}

abstract class AuthBase {
  Stream<MyUser> get onAuthStateChanged;
  Future<MyUser> currentUser();
  Future<MyUser> signInAnonymously();
  Future<MyUser> signInWithGoogle();
  Future<void> signOut();
}

class Auth implements AuthBase {

  var _initialization,_firebaseAuth;

  Auth(){
    _intializeMe();
    _firebaseAuth =  FirebaseAuth.instance;
  }

  _intializeMe() async {
    FirebaseApp _initialization = (await Firebase.initializeApp());
  }

  MyUser _userFromFirebase(User user) {
    if (user == null) {
      return null;
    }
    return MyUser(uid: user.uid);
  }

  @override
  Stream<MyUser> get onAuthStateChanged {
    return _firebaseAuth.authStateChanges().map(_userFromFirebase);
  }

  @override
  Future<MyUser> currentUser() async {
    final user = await _firebaseAuth.currentUser;
    return _userFromFirebase(user);
  }

  @override
  Future<MyUser> signInAnonymously() async {

final authResult = await _firebaseAuth.signInAnonymously();
return _userFromFirebase(authResult.user);
  }

  @override
  Future<MyUser> signInWithGoogle() async {
final googleSignIn = GoogleSignIn();
final googleAccount = await googleSignIn.signIn();
if (googleAccount != null) {
  final googleAuth = await googleAccount.authentication;
  if (googleAuth.accessToken != null && googleAuth.idToken != null) {
    final authResult = await _firebaseAuth.signInWithCredential(
      GoogleAuthProvider.credential(
        idToken: googleAuth.idToken,
        accessToken: googleAuth.accessToken,
      ),
    );
    return _userFromFirebase(authResult.user);
  } else {
    throw PlatformException(
      code: 'ERROR_MISSING_GOOGLE_AUTH_TOKEN',
      message: 'Missing Google Auth Token',
    );
  }
} else {
  throw PlatformException(
    code: 'ERROR_ABORTED_BY_USER',
    message: 'Sign in aborted by user',
  );
}
  }


  @override
  Future<void> signOut() async {
    final googleSignIn = GoogleSignIn();
    await googleSignIn.signOut();
    final facebookLogin = FacebookLogin();
    await facebookLogin.logOut();
    await _firebaseAuth.signOut();
  }
}
`