[SEVERE] Could not pass event BlockBreakEvent to CraftBookMechanisms
org.bukkit.event.EventException
	at org.bukkit.plugin.java.JavaPluginLoader$1.execute(JavaPluginLoader.java:341)
	at org.bukkit.plugin.RegisteredListener.callEvent(RegisteredListener.java:62)
	at org.bukkit.plugin.SimplePluginManager.fireEvent(SimplePluginManager.java:477)
	at org.bukkit.plugin.SimplePluginManager.callEvent(SimplePluginManager.java:462)
	at net.minecraft.server.ItemInWorldManager.breakBlock(ItemInWorldManager.java:278)
	at net.minecraft.server.ItemInWorldManager.dig(ItemInWorldManager.java:126)
	at net.minecraft.server.NetServerHandler.a(NetServerHandler.java:547)
	at net.minecraft.server.Packet14BlockDig.handle(SourceFile:46)
	at net.minecraft.server.NetworkManager.b(NetworkManager.java:282)
	at net.minecraft.server.NetServerHandler.d(NetServerHandler.java:109)
	at net.minecraft.server.ServerConnection.b(SourceFile:35)
	at net.minecraft.server.DedicatedServerConnection.b(SourceFile:30)
	at net.minecraft.server.MinecraftServer.q(MinecraftServer.java:578)
	at net.minecraft.server.DedicatedServer.q(DedicatedServer.java:213)
	at net.minecraft.server.MinecraftServer.p(MinecraftServer.java:474)
	at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:405)
	at net.minecraft.server.ThreadServerApplication.run(SourceFile:539)
Caused by: java.lang.NullPointerException
	at com.sk89q.craftbook.mech.Door.hasEnoughBlocks(Door.java:573)
	at com.sk89q.craftbook.mech.Door.onBlockBreak(Door.java:531)
	at com.sk89q.craftbook.MechanicManager.dispatchBlockBreak(MechanicManager.java:206)
	at com.sk89q.craftbook.bukkit.MechanicListenerAdapter$MechanicBlockListener.onBlockBreak(MechanicListenerAdapter.java:159)
	at sun.reflect.GeneratedMethodAccessor145.invoke(Unknown Source)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:601)
	at org.bukkit.plugin.java.JavaPluginLoader$1.execute(JavaPluginLoader.java:339)
	... 16 more



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2012-10-20 01:31:24 [WARNING] CraftBook mechanic: Failed to think for com.sk89q.craftbook.ic.SelfTriggeredICMechanic
java.util.ConcurrentModificationException
	at java.util.ArrayList$Itr.checkForComodification(ArrayList.java:819)
	at java.util.ArrayList$Itr.next(ArrayList.java:791)
	at org.bukkit.craftbukkit.CraftWorld.getPlayers(CraftWorld.java:682)
	at com.sk89q.craftbook.gates.world.PotionInducer.think(PotionInducer.java:55)
	at com.sk89q.craftbook.ic.SelfTriggeredICMechanic.think(SelfTriggeredICMechanic.java:51)
	at com.sk89q.craftbook.MechanicManager.think(MechanicManager.java:628)
	at com.sk89q.craftbook.bukkit.MechanicClock.run(MechanicClock.java:35)
	at org.bukkit.craftbukkit.scheduler.CraftTask.run(CraftTask.java:52)
	at org.bukkit.craftbukkit.scheduler.CraftScheduler.mainThreadHeartbeat(CraftScheduler.java:321)
	at net.minecraft.server.MinecraftServer.q(MinecraftServer.java:510)
	at net.minecraft.server.DedicatedServer.q(DedicatedServer.java:213)
	at net.minecraft.server.MinecraftServer.p(MinecraftServer.java:474)
	at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:405)
	at net.minecraft.server.ThreadServerApplication.run(SourceFile:539)