Crash report (Batching chunks java.util.ConcurrentModificationException)

Sudden crash, I attach files.

Description: Batching chunks

java.util.ConcurrentModificationException
	at java.util.ArrayList$Itr.checkForComodification(Unknown Source)
	at java.util.ArrayList$Itr.remove(Unknown Source)
	at aqa.a(SourceFile:1735)
	at bed.e(SourceFile:690)
	at aqp.s(SourceFile:63)
	at cmy.b(SourceFile:140)
	at cmr.a(SourceFile:71)
	at cmr.run(SourceFile:31)
	at java.lang.Thread.run(Unknown Source)