Display generic error message on unsuccessful sign-in #27
Description
Issue summary
On unsuccessful signin, the FirebaseUI is flushed and the user can attempt to sign in again. Currently, the error that occurs is printed to the console log. We instead want to display a generic error message to the user that prompts them to try again.
Expected behavior
On unsuccessful sign-in, display a generic error message to the user that asks them to try again.
Actual behavior
On unsuccessful sign-in, the error message is only displayed to the console log.