Great, simple concept and fun game loop. It had me really addicted when I played it earlier today. The game crashed as I was getting close to finishing out my skill tree though. Is your web export made using Godot 4.4?
I don't know what triggered it but, it was very similar to the out of memory errors we used to see in 4.4 with webkit audio workers that was fixed in 4.5. After I play a few more games maybe I'll come back and use the web inspector to see what's going on here.