Don't show UI before auth

[Yamakasi]

Is your feature request related to a problem? Please describe.
When you use credentials the UI is still (empty) shown without being authenticated

Describe the solution you'd like
Blank page before auth

Describe alternatives you've considered
(Another) Nginx reverse proxy in front of it all

[Joxit]

Hi, thank you for using my project 😄

There is already an empty page when someone tries to connect to it without having the rights.
But I can create a page with a big 401 / 403 / 404 🤔

[Joxit]

We cannot hide the UI before auth, but I added a new error page