Hi,
If you open the sign in popout and click Sign in without filling any of the fields, the page reloads and a error messages says you've submitted an invalid email and password.
However, shouldn't these fields just be required so the user is forced to write something to the field before submitting? It's how it works in the Sign in page.
I made a video showing the issue:
https://www.screencast.com/t/06pHp0XaNz
Regards