I'm surprised! There's nothing about the way I handle projectiles that should be even a little unstable.
This game engine struggles with HTML builds for reasons outside the developer's control (even an empty project, doing nothing, can't reach a stable 60fps...) so I highly recommend- if you like the gameplay, but feel like it's too slow, download it and run locally! It'll be so much better running at a smooth 60fps.
(and I'll take a look to see if I can replicate the crash)