Crystal Networker

19:29:47] [Client thread/ERROR] [FML]: Exception caught during firing event net.minecraftforge.event.world.WorldEvent$Unload@4f6531f8:
java.util.ConcurrentModificationException
	at java.util.HashMap$HashIterator.nextNode(HashMap.java:1429) ~[?:1.8.0_25]
	at java.util.HashMap$KeyIterator.next(HashMap.java:1453) ~[?:1.8.0_25]
	at java.util.Collections$UnmodifiableCollection$1.next(Collections.java:1042) ~[?:1.8.0_25]
	at Reika.ChromatiCraft.Magic.CrystalNetworker.clearOnUnload(CrystalNetworker.java:61) ~[CrystalNetworker.class:?]
	at cpw.mods.fml.common.eventhandler.ASMEventHandler_618_CrystalNetworker_clearOnUnload_Unload.invoke(.dynamic) ~[?:?]
	at cpw.mods.fml.common.eventhandler.ASMEventHandler.invoke(ASMEventHandler.java:54) ~[ASMEventHandler.class:?]
	at cpw.mods.fml.common.eventhandler.EventBus.post(EventBus.java:138) [EventBus.class:?]
	at net.minecraft.client.Minecraft.func_71353_a(Minecraft.java:2142) [bao.class:?]
	at net.minecraft.client.Minecraft.func_71403_a(Minecraft.java:2135) [bao.class:?]
	at net.minecraft.client.Minecraft.func_71398_f(Minecraft.java:1127) [bao.class:?]
	at net.minecraft.client.Minecraft.func_99999_d(Minecraft.java:909) [bao.class:?]
	at net.minecraft.client.main.Main.main(SourceFile:148) [Main.class:?]
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[?:1.8.0_25]
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[?:1.8.0_25]
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[?:1.8.0_25]
	at java.lang.reflect.Method.invoke(Method.java:483) ~[?:1.8.0_25]
	at net.minecraft.launchwrapper.Launch.launch(Launch.java:135) [launchwrapper-1.11.jar:?]
	at net.minecraft.launchwrapper.Launch.main(Launch.java:28) [launchwrapper-1.11.jar:?]
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[?:1.8.0_25]
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[?:1.8.0_25]
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[?:1.8.0_25]
	at java.lang.reflect.Method.invoke(Method.java:483) ~[?:1.8.0_25]
	at org.multimc.onesix.OneSixLauncher.launchWithMainClass(OneSixLauncher.java:286) [NewLaunch.jar:?]
	at org.multimc.onesix.OneSixLauncher.launch(OneSixLauncher.java:376) [NewLaunch.jar:?]
	at org.multimc.EntryPoint.listen(EntryPoint.java:165) [NewLaunch.jar:?]
	at org.multimc.EntryPoint.main(EntryPoint.java:54) [NewLaunch.jar:?]