Expose errMsgId to subscribers

[joshfriend]

If the fingerprint authentication fails with an error like FINGERPRINT_ERROR_LOCKOUT, the UI should display an error for a longer period of time than if the error is FINGERPRINT_ACQUIRED_TOO_FAST for example. There is currently no way to know what the specific error condition of the reader is. The error id should be passed along inside FingerprintAuthenticationException

[Mauin]

I can think about passing the ID of the error message along.

Generally all errors that cause the Fingerprint sensor to "lock down" (FINGERPRINT_ERROR_LOCKOUT is one example of this) will be passed in .onError(). Recoverable Errors such as moving the finger too fast will be delivered in .onNext(). This distinction between .onNext and .onError already gives a hint at the severity of the issue.

[joshfriend]

Thanks for pointing that out! It does help a lot, but if the subscriber is disposed on rotation, cancellationSignal.cancel() causes FINGERPRINT_ERROR_CANCELED to be sent to the onAuthenticationError callback. It would be nice to be able to distinguish this from an error condition that should be shown to the user.