Ok, thank you this is super important info! I tried quickly myself but didn't appear to have the same issue, but hearing this and seeing how laggy it is in Firefox compared to Chrome, I can already tell the bug here has something to do with the horrendous optimization that I accidentally did. And by the sounds of it the game might even get stuck in some sort of infinite loop, hence the Firefox notification.
But yes, thank you so much for taking the time to test it and report back to me, helps me a lot :) In the update I'm working on, I've already improved the optimization and loading so this might have been fixed.