"Invalid credential" error returned instead of "user already exists"

[cbush]

Using username/password authentication to log in as an existing user with register == true, I get the "invalid credential" error code, not the "user already exists" error. Likewise, if I log in as a non-existent user with register == false, I get "invalid credential" instead of "user does not exist". Is this a bug?

I have checked that username/authentication is enabled on my instance and email validation is disabled. I can see that the users are being created the first time.

Goals

I would like to have special code to handle the case where the user already exists, but with the same error returned I can't distinguish this error from any other auth error.

Expected Results

userAlreadyExists error code (613)

Actual Results

invalidCredential error code (611)

Steps to Reproduce

1. Log in (registering a new user)
2. Log out
3. Log in again as the same user (register still set to true)
4. Handle error and check the code

Code Sample

let creds = SyncCredentials.usernamePassword(username: name, password: "password", register: true);

SyncUser.logIn(with: creds, server: Constants.AUTH_URL, onCompletion: { [weak self](user, err) in
    if let _ = user {
        // login successful
    } else if let error = err as? SyncAuthError {
        switch error.code {
            case .userDoesNotExist: // never hit!
                fatalError(error.localizedDescription);
            case .userAlreadyExists: // never hit!
                fatalError(error.localizedDescription);
            case .invalidCredential: // this is always the case
                fatalError(error.localizedDescription);
            default:
                break;
        }

    }
})

Version of Realm and Tooling

• Realm Object Server Version: 3.26.2
• Flavor:
  • [x] Cloud
  • [ ] Self-hosted
• Server OS & Version: ? (e.g. CentOS 6)
• Client SDK Version: RealmSwift 3.16.2
• Client OS & Version: ?