coreNotInitialized function
Throws a consistent error message if the user attempts to initializes core without it being available on the underlying platform.
Implementation
FirebaseException coreNotInitialized() {
String message = '''
Firebase has not been correctly initialized.
Usually this means you've attempted to use a Firebase service before calling `Firebase.initializeApp`.
View the documentation for more information: https://firebase.flutter.dev/docs/overview#initialization
''';
return FirebaseException(
plugin: 'core', code: 'not-initialized', message: message);
}