Hey, thanks for the heads-up!
I saw that the ren'py website was down yesterday, so I'm wondering if maybe it needs to establish a connection/load some more assets for the web version from their server and that broke it? Could you try starting it today/some time from now and see if the issues still persist?
The error message refers to code that is supplied from ren'py itself, so if this wasn't just temporary, I might get into contact with the maintainer so they know about it if it's a bug with the engine.
If you want to send us longer error logs, you can also send us an e-mail at nothack.europa@gmail.com. Thanks again for letting us know~