Additional fields for NativeFirebaseError.

[johnkmzhou]

It would be nice for NativeFirebaseError to adhere more closer to firebase.auth.Error by adding email and credential fields:

Errors with the code auth/account-exists-with-different-credential will have the additional fields email and credential which are needed to provide a way to resolve these specific errors.

[mikehardy]

@johnkmzhou if you reach in to node_modules and add some print statements around where the error is generated, you can see if the data is actually available. I am not sure it is, there is no mention of it in the native Android doc: https://firebase.google.com/docs/reference/android/com/google/firebase/auth/FirebaseAuthUserCollisionException or iOS https://firebase.google.com/docs/reference/ios/firebaseauth/api/reference/Classes/FIRAuth#-createuserwithemail:password:completion:

They specifically mention in iOS:

FIRAuthErrorCodeEmailAlreadyInUse - Indicates the email used to attempt sign up already exists. Call fetchProvidersForEmail to check which sign-in mechanisms the user used, and prompt the user to sign in with one of those.

and

FIRAuthErrorCodeAccountExistsWithDifferentCredential - Indicates the email asserted by the credential (e.g. the email in a Facebook access token) is already in use by an existing account, that cannot be authenticated with this sign-in method. Call fetchProvidersForEmail for this user’s email and then prompt them to sign in with any of the sign-in providers returned. This error will only be thrown if the “One account per email address” setting is enabled in the Firebase console, under Auth settings.

...which is the strategy I have used with success

For native to add the information you want means native would have to call fetchProvidersForEmail itself - extra roundtrips on the network etc - is that what you mean?

[johnkmzhou]

Taking a look at the nativeError the fields aren't available. So it would be great for the the native code to provide it. Email from getEmail in Android's FirebaseAuthUserCollisionException and the NSError.userInfo dictionary object in iOS's AuthErrorUserInfoEmailKey.

I don't need native to call fetchProvidersForEmail. I can do that from my own code.

[mikehardy]

PRs happily accepted 🙏 - we rely on the community to move things like this forward though, in the absence of a PR, likely nothing will happen