It's there in the title: if you don't have a chat room, the "Set your rooom's culture" notification takes you to a 404 page. Well, that makes sense, because I assume it's trying to take me to my room, but I don't have one. But it seems like either the notification shouldn't be displayed to people who don't have a room, or it should re-direct people to some sort of landing page explaining what they're missing.
I deliberated among bug (since this presumably isn't an intentional outcome) and feature-request (since I'd like it to be set up not to invite users to this presumably unintended experience), as it isn't really either. Please feel free to re-tag.