Concurrent modification when iterating over game spaces during scheduled stop to close them

[haykam821]

Nucleoid Extras iterates over every open game space in the game space manager to close them:

nucleoid-extras/src/main/java/xyz/nucleoid/extras/scheduled_stop/ScheduledStop.java

Lines 83 to 85 in 2b74876

	for (var gameSpace : GameSpaceManager.get().getOpenGameSpaces()) {
	gameSpace.close(GameCloseReason.CANCELED);
	}

However, closing a game space removes it from the same list in the game space manager that is being iterated over.

Using the GameSpaceManager.startClosing method, which calls GameSpaceManager#close internally, would solve this issue as its implementation of this behavior copies the list before iterating over the game spaces.