Hi there! Thank you for letting me know about the error!
I haven't been able to replicate this on my end, and my friend hasn't gotten it to occur on his system, but!—I could 💯 see it happening if the connection dropped during loading.
Try Ctrl+F5 or Cmd+Shift+R for a hard refresh.
Incognito/private mode will also help if your browser already cached an earlier failed version.
Since slower connections impacts this game when played via web, downloading the Windows version is the best workaround. 🎉