FirebaseURL empty => error, how to avoid error message?

How to use project containing FirebaseDB component without FirebaseURL configured?
I would like to create a program that allows communication between two or more smartphones
Communication can take place via sms or via FirebaseDB, depending on the current configuration
If the app is configured to communicate via sms, the settings related to FirebaseDB may be empty
But if the FirebaseURL field is empty, the app reports an error
The question is: how to avoid the error signaling when the app has an empty FirebaseURL field?

Why does the url need to be empty? Just don’t use firebase as the communication medium if user chooses SMS ?

Beacuse FirebaseDB account may be not available

Because of no wifi or data connection (in which the SMS option wouldn’t work either)

Do you get an error message if “the Firebase account is not available” ?

Yes, if FirebaseURL is empty and FirebaseToken is empty, we get this error
“Error from Companion: Invalid Firebase url specified” when app is starting and
“Attempt to invoke virtual method ‘com.firebase.client.Firebase com.firebase.client.Firebase.child(java.lang.String)’ on a null object reference” when i tap on image

No, I mean when you have a FirebaseURL and FirebaseToken in place. When/under what circumstances is Firebase “not available” and do you then get errors? If none, then there is no issue…