Unsaved changes cause exit bugs

[soxfox42]

If a cart is running with unsaved changes and you try to exit through the menu, the menu will disappear and leave only the scrolling background. You can return to the menu by pressing escape.
Also, if a cart is running and there are unsaved changes, TIC-80 will crash completely if you try to close using the window controls, but then select the option to not quit.

Tested on:

• macOS 12 arm64 (running x86_64 TIC-80 with Rosetta 2)
• Manjaro Linux 21 x86_64

[sogaiu]

I think this may be related to #1969.

[soxfox42]

Ah yep, that's the same as the first of the two bugs here.

[nesbox]

dup of #1969