FPVSignInWithPhoneAuthCredential.kt

private fun signInWithPhoneAuthCredential(credential: PhoneAuthCredential) {
        auth.signInWithCredential(credential)
            .addOnCompleteListener(this) {
                if (it.isSuccessful) {
                  // Successful mean that the phone is verified, so do whatever you want here.
                } else {
                    Toast.makeText(
                        this,
                        "Something went wrong, try again later please.",
                        Toast.LENGTH_LONG).show()
                }
            }
    }