Remove early auth error when no user or pass

[BanovMiroslav]

When not adding a user and pass, there is a specific error being sent. But this case is already handled by the verify callback, and it is easier and more natural to send a prettier error response to the end-user if there is no special handling of the case where user and password are not provided.

[Fonger]

@jaredhanson

+1 for this. This is obviously a bug!
jaredhanson/passport#466

However I think you should simply use this.error instead of removing it in this line:
https://github.com/jaredhanson/passport-local/blob/master/lib/strategy.js#L75

[vuaru]

@Fonger
Then you're assuming that not having a username or password is an error, which might not always be the case. Determining this is the job of the verify callback, imo.

[rwky]

@BanovMiroslav if you make a PR against https://github.com/passport-next/passport-local this will get looked into.