Bug: Page 404 is shown in Puzzle Themes -> By Openings -> 'More >' (if user is not logged in)

I am often doing puzzles without logging in, because I get a different mix of things this way and I noticed today that we have Page 404 link here, if a user that is not logged into lichess.org clicks on the More > link in the screenshot: https://lichess.org/training/themes https://i.imgur.com/ZwB5ED7.png https://i.imgur.com/Pof3aEu.png I am fairly certain this problem is new and was not present 3-4 days ago. I can verify the issue on Firefox, Edge on desktop and on IPhone in Safari.

Great bug report, @dirkster99 ! You should use the GitHub issues for a higher chance of getting picked up: https://github.com/lichess-org/lila/issues/17607