Propagating onEvent errors of EventListener not handled

[kaushiknsanji]

In the Step - "Display data from Firestore", the provided code does not handle the case of propagating the Listen errors to the protected method onError() of FirestoreAdapter. If propagated, then only the user will be able to see a Snackbar in case of any Listen errors occurring due to improper Query, in the onEvent() callback of EventListener. This onError() method is overidden by subclasses of FirestoreAdapter to provide their own implementation for handling the FirebaseFirestoreException error passed to it.