Game suddenly stopped and declared a winner

Game exception occurred:

java.util.ConcurrentModificationException
Server version: 1.4.52-V7-beta5 (build: 2023-12-23 13:50)
Stack trace:
java.util.ArrayList$Itr.checkForComodification(ArrayList.java:909)
java.util.ArrayList$Itr.remove(ArrayList.java:873)
mage.server.User.onLostConnection(User.java:200)
mage.server.SessionManagerImpl.lambda$disconnect$1(SessionManagerImpl.java:130)
java.util.Optional.ifPresent(Optional.java:159)
mage.server.SessionManagerImpl.disconnect(SessionManagerImpl.java:129)
mage.server.Session.fireCallback(Session.java:457)
mage.server.User.lambda$fireCallback$0(User.java:260)
java.util.Optional.ifPresent(Optional.java:159)
mage.server.User.fireCallback(User.java:259)
mage.server.game.GameSessionWatcher.lambda$update$0(GameSessionWatcher.java:54)
java.util.Optional.ifPresent(Optional.java:159)
mage.server.game.GameSessionWatcher.update(GameSessionWatcher.java:54)
mage.server.game.GameController.updateGame(GameController.java:793)
mage.server.game.GameController.lambda$init$3aa0d15c$1(GameController.java:122)
mage.game.events.EventDispatcher.fireEvent(EventDispatcher.java:28)
mage.game.events.TableEventSource.fireTableEvent(TableEventSource.java:44)
mage.game.GameImpl.fireUpdatePlayersEvent(GameImpl.java:3100)
mage.game.GameImpl.playPriority(GameImpl.java:1616)
mage.game.turn.Step.priority(Step.java:67)
mage.game.turn.Phase.playStep(Phase.java:204)
mage.game.turn.Phase.play(Phase.java:90)
mage.game.turn.Turn.play(Turn.java:137)
mage.game.GameImpl.playTurn(GameImpl.java:1112)
mage.game.GameImpl.play(GameImpl.java:1019)
mage.game.GameImpl.start(GameImpl.java:995)
mage.server.game.GameWorker.call(GameWorker.java:34)
java.util.concurrent.FutureTask.run(FutureTask.java:266)
java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
java.lang.Thread.run(Thread.java:748)

Start with mage.server.User.onLostConnection and mage.server.SessionManagerImpl.disconnect, then trace the callback path through GameSessionWatcher.update. Reproduce or investigate the ConcurrentModificationException from the supplied stack trace; done means disconnect handling no longer stops the game or incorrectly declares a winner.

Written by the indexing model from the issue text.