This one was pretty nasty, as it crashed TIC-80 itself, and took some major debugging as the effects were "random" based on the C linker and compiler! It was ultimately some really sloppy memory management (or rather, not bothering to check at all), and makes me concerned that doing 'safe' and 'sandboxed' things will still result in nasty undefined behavior!
But yeah, hopefully they either revert the lua version or come up with a way to switch lua versions on a per-cart metadata or something!
If you're curious, here's the issue report: