Hello,

We tested this function with our account and it works well. The error saying about the fact that Facebook doesn’t provide an email means that API response doesn’t have a user email and that is why registration can’t be complete. We can’t know the reason why email is not in the Facebook response. It happens for some accounts only.
https://gyazo.com/8ded42c5bf717993d83f1b2fb2a6733b

Kind Regards
XTemos Studio