Thread stall during mod constructions prevents closing the game

[UpcraftLP]

If the game stalls during mod construction, it becomes impossible to exit the game, except for manually killing the process.

The window however does stay responsive and updates the displayed memory and CPU values, so therefore it should be possible to react to the user trying to close the window via the X button or ALT+F4 keyboard shortcut etc..

To reproduce, simply insert a dummy infinite loop into a mod constructor:

public MyMod() throws Throwable {
	while(true) {
		Thread.onSpinWait();
	}
}