Flutterfire: [📚] [Firebase Crashlytics] Handling uncaught errors

[awhitford]

The guidance here is no longer compatible with Firebase Crashlytics 0.2.0 because the FirebaseApp must first be initialized -- you get this exception:

[VERBOSE-2:ui_dart_state.cc(166)] Unhandled Exception: [core/no-app] No Firebase App '[DEFAULT]' has been created - call Firebase.initializeApp()
#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      FirebaseCrashlytics.instance (package:firebase_crashlytics/src/firebase_crashlytics.dart:31:62)
#3      main (package:kozzeter/main.dart:21:46)
#4      _runMainZoned.<anonymous closure>.<anonymous closure> (dart:ui/hooks.dart:233:25)
#5      _rootRun (dart:async/zone.dart:1190:13)
#6      _CustomZone.run (dart:async/zone.dart:1093:19)
#7      _runZoned (dart:async/zone.dart:1630:10)
#8      runZonedGuarded (dart:async/zone.dart:1618:12)
#9      _runMainZoned.<anonymous closure> (dart:ui/hooks.dart:225:5)
#10     _startIsolate.<anonymous closure> (dart:isolate-patch/isolate_patch.dart:301:19)
#11     _RawReceivePortImpl._handleMessage (dart:isolate-patch<…>

[masewo]

You also get this exception when trying to use FirebaseCrashlytics.instance.log() before Firebase.initializeApp() was called.

And you really have to await the Firebase.initializeApp() before being able to call FirebaseCrashlytics.instance.log().

[cbenhagen]

You might want to run Firebase.initializeApp() in your main():
https://github.com/FirebaseExtended/flutterfire/issues/3271#issuecomment-677703143

[stardustxx]

Can confirm that adding Firebase.initializeApp() to main() works

You may also see an exception like this when you make main() an async function:

Unhandled Exception: ServicesBinding.defaultBinaryMessenger was accessed before the binding was initialized.
If you're running an application and need to access the binary messenger before `runApp()` has been called (for example, during plugin initialization), then you need to explicitly call the `WidgetsFlutterBinding.ensureInitialized()` first.

Add the method call WidgetsFlutterBinding.ensureInitialized(); to your main can solve this

Your main() will look something like:

void main() async {
  WidgetsFlutterBinding.ensureInitialized();

  await Firebase.initializeApp();

  runZonedGuarded(() => runApp(new App()), FirebaseCrashlytics.instance.recordError);
}

[awhitford]

For the record, I was able to get this to work. The purpose of this issue is to ensure that the documentation gets updated.