Empty error box on email entry in login input field

Summary

Empty error box on email entry in login input field

Steps to reproduce

1. Go to login page
2. Enter an email address instead of a username
3. Submit

Platform information

Cross-platform probably web, should check mobile before closing though.

What is the current bug behavior?

Empty error box is shown

What is the expected correct behavior?

There should be a URL regex check, that checks for emails and displays an appropriate error.

Relevant logs and/or screenshots

Possible fixes

(If you can, link to the line of code that might be responsible for the problem)