ConcurrentModificationError in GlamerSpinnersEffect

GameImpl.playPriority
java.util.ConcurrentModificationException
at java.util.ArrayList$Itr.checkForComodification(ArrayList.java:911)
at java.util.ArrayList$Itr.next(ArrayList.java:861)
at mage.cards.g.GlamerSpinnersEffect.apply(GlamerSpinners.java:115)
at mage.abilities.AbilityImpl.resolveMode(AbilityImpl.java:229)
at mage.abilities.AbilityImpl.resolve(AbilityImpl.java:213)
at mage.abilities.TriggeredAbilityImpl.resolve(TriggeredAbilityImpl.java:273)
at mage.game.stack.StackAbility.resolve(StackAbility.java:85)
at mage.game.GameImpl.resolve(GameImpl.java:1845)
at mage.game.GameImpl.playPriority(GameImpl.java:1766)
at mage.game.turn.Step.priority(Step.java:73)
at mage.game.turn.Phase.playStep(Phase.java:205)
at mage.game.turn.Phase.play(Phase.java:91)
at mage.game.turn.Turn.play(Turn.java:132)
at mage.game.GameImpl.playTurn(GameImpl.java:1183)
at mage.game.GameImpl.play(GameImpl.java:1090)
at mage.game.GameImpl.start(GameImpl.java:1066)
at mage.server.game.GameWorker.call(GameWorker.java:35)
at mage.server.game.GameWorker.call(GameWorker.java:16)
at java.util.concurrent.FutureTask.run(FutureTask.java:266)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
at java.lang.Thread.run(Thread.java:750)

ETB effect of [[Glamer Spinners]] targeted Puresight Merrow which was enchanted with a Shield of the Oversoul. Only one legal target to attach, an Apothecary Initiate, but error completely broke the game when asking for choice. Rollback didn't even restore the state correctly. Neither player was able to regain priority afterwards.

Following repeated error:
java.lang.IllegalStateException: Error in unit tests =>[GAME edf33d43-3d39-4cb5-b3da-012553318b89] GameWorker.call
java.lang.IllegalStateException: Error in unit tests
at mage.game.GameImpl.playPriority(GameImpl.java:1831)
at mage.game.turn.Step.priority(Step.java:73)
at mage.game.turn.Phase.playStep(Phase.java:205)
at mage.game.turn.Phase.play(Phase.java:91)
at mage.game.turn.Turn.play(Turn.java:132)
at mage.game.GameImpl.playTurn(GameImpl.java:1183)
at mage.game.GameImpl.play(GameImpl.java:1090)
at mage.game.GameImpl.start(GameImpl.java:1066)
at mage.server.game.GameWorker.call(GameWorker.java:35)
at mage.server.game.GameWorker.call(GameWorker.java:16)
at java.util.concurrent.FutureTask.run(FutureTask.java:266)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
at java.lang.Thread.run(Thread.java:750)