java.util.ConcurrentModificationException
	at java.util.ArrayList$Itr.checkForComodification(ArrayList.java:819)
	at java.util.ArrayList$Itr.next(ArrayList.java:791)
	at go.b(SourceFile:154)
	at gr.b(WorldServer.java:129)
	at net.minecraft.server.MinecraftServer.q(MinecraftServer.java:620)
	at ft.q(DedicatedServer.java:241)
	at net.minecraft.server.MinecraftServer.p(MinecraftServer.java:560)
	at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:466)
	at ep.run(SourceFile:539)