noAppExists function Null safety

FirebaseException noAppExists(
  1. String appName
)

Throws a consistent cross-platform error message when usage of an app occurs but no app has been created.

Implementation

FirebaseException noAppExists(String appName) {
  return FirebaseException(
      plugin: 'core',
      code: 'no-app',
      message:
          "No Firebase App '$appName' has been created - call Firebase.initializeApp()");
}