'no default app' exception after Firebase has been initialized

Question

I am initializing Firebase with a specific project. I am then passing the resulting FirebaseApp to FirebaseFirestore.instanceOf method. I am using hard coded config values, because eventually this implementation will use multiple projects.

When I try to write to a collection, I get the following exception...

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

Here is a minimal reproducible example, with a comment indicating the the line that throws the exception...

import 'package:cloud_firestore/cloud_firestore.dart';
import 'package:firebase_core/firebase_core.dart';
import 'package:flutter/material.dart';

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

class MyApp extends StatelessWidget {
  const MyApp({Key? key}) : super(key: key);
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: const MyHomePage(),
    );
  }
}

class MyHomePage extends StatefulWidget {
  const MyHomePage({Key? key}) : super(key: key);
  @override
  State<MyHomePage> createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {
  @override
  void initState() {
    super.initState();
    _asyncInit();
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: const Text("Test App"),
      ),
      body: Container(),
    );
  }

  Future<void> _asyncInit() async {
    var app = await Firebase.initializeApp(
      name: "my-throwaway-project",
      options: const FirebaseOptions(
        apiKey: "AIzaSyBXOxFf_iXaer4tX-sE8eRrh77VftTKZI0",
        appId: "1:980810897373:android:b1a4bcd50cd76712868834",
        messagingSenderId: "980810897311",
        projectId: "my-throwaway-project",
      ),
    );

    var db = FirebaseFirestore.instanceFor(app: app);
    await db.collection("test1").add({"field1":"value1"}); // this line throws the exception
  }
}

Based on the docs, it seems like I am doing everything correctly to initialize, but yet there is still an error.

Answer 1

Normally we initialize firebase on main before runapp.. may be that is the issue..