The static pages hosted at http://paperjs.org as the Paper.js website, generated from https://github.com/paperjs/paperjs.org by running it through https://github.com/studiomoniker/woods – Automatically regenerated and pushed once a day.
If you by accident put something along the lines of while(true) etc. into the field, it's hard to recover your work since on every reload the script will be executed immidiately, the tab will freeze, and you don't have a chance to correct the mistake
Opening https://paperjs.org/ currently leads to a TLS certificate error about github.com.
To my knowledge, at least nowadays, GitHub Pages is capable of serving sites over HTTPS by default, as well as to create the certificates automatically (via Let's Encrypt). Given that this is not happening currently, perhaps the DNS for this domain is not up to date with the current requirements for custom domains?