It is also nothing for me in a Firefox fork with almost all add-ons disabled. Error console says there's a bunch of "class is a reserved identifier" and syntax errors of missing semicolons (before main() can even run).
My guess it's trying to use some bleeding edge emcascript stuff which borks the parsing in non-bleeding edge browsers.
If you run into problems, I'd love to know specific details - this is an experiment to see what was achievable with Dweb tools like IPFS, WebTorrent, Gun on browsers, with a big site like the Archive. It certainly pushes the edge of browsers - and does use the latest ES6 features without much attempt to support older browsers (unlike the production site at archive.org). We only currently test in the latest Chrome & Firefox, though it seems to work (mostly) on current Safari on iPad and iPhone and I heard its working on Android though I haven't seen it yet.
> ... and does use the latest ES6 features without much attempt to support older browsers (unlike the production site at archive.org)
Except the wayback machine which recently changed it's interface to be entirely JS dependent and fails on older browsers. And the old interface is no longer accessible.