+1, but I tried patiently to move the mouse over the X (close tab button) and clicked a few times... one minute later it closed and I got away without a hard reset.

This also crashed firefox on Linux for me.

I also experience crashes from time to time. The project is compiled into webassembly(wasm), and I think the wasm has yet to be tested more with bigger code base.

Might be that the version of firefox I was using (since it's a lab machine) is outdated. Wasm is right now bleeding edge technology, so it's going to be a bit of a weird side for a while as machines are updated for compatibility

Yeah, I'm guessing that too. When I load the page in firefox my new ubuntu 16 machine randomly freezes, had to reset and update the drivers suspecting it was some hardware/driver issue. However, chrome is working pretty well.