Adding a way to go back on error pages
Description
I removed myself from an old project and it was still there in my projects page. I clicked on the project to see if the repository was visible (it's a private repo). I got a 404 as expected, but there was no way of going back to GitLab without going to the address bar and manually entering a new URL.
Proposal
Put some kind of "Go Back" button, etc. on the error pages to improve the user experience.