Unsaved changes screen fails to load on quit from menu

[MineRobber9000]

How to reproduce:

1. Start TIC-80 1.0.
2. Make a change to the default cart.
3. Run the cart.
4. Enter the menu with the cart running.
5. Select QUIT TIC-80

Expected behavior: The unsaved changes screen appears, asking me if I really want to exit with unsaved changes.

What actually happens: The menu seemingly disappears.

I say "seemingly" because pressing either A or B reveals the previous menu to still be active, albeit hidden from view. Pressing B at this stage will resume the game.