craftbook crash

2013-05-11 21:29:13 [INFO] Chlorobastion issued server command: /home
2013-05-11 21:29:19 [WARNING] [CraftBook] Task #383503 for CraftBook v2123-024220d generated an exception
java.lang.IllegalArgumentException: Null ChangedSign found: (-100.0, 2.0, -10.0)
	at org.apache.commons.lang.Validate.notNull(Validate.java:203)
	at com.sk89q.craftbook.circuits.ic.AbstractChipState.<init>(AbstractChipState.java:26)
	at com.sk89q.craftbook.circuits.ic.families.FamilySISO$ChipStateSISO.<init>(FamilySISO.java:53)
	at com.sk89q.craftbook.circuits.ic.families.FamilySISO.detect(FamilySISO.java:40)
	at com.sk89q.craftbook.circuits.ic.ICMechanic$1.run(ICMechanic.java:94)
	at org.bukkit.craftbukkit.v1_5_R3.scheduler.CraftTask.run(CraftTask.java:53)
	at org.bukkit.craftbukkit.v1_5_R3.scheduler.CraftScheduler.mainThreadHeartbeat(CraftScheduler.java:345)
	at net.minecraft.server.v1_5_R3.MinecraftServer.r(MinecraftServer.java:513)
	at net.minecraft.server.v1_5_R3.DedicatedServer.r(DedicatedServer.java:226)
	at net.minecraft.server.v1_5_R3.MinecraftServer.q(MinecraftServer.java:477)
	at net.minecraft.server.v1_5_R3.MinecraftServer.run(MinecraftServer.java:410)
	at net.minecraft.server.v1_5_R3.ThreadServerApplication.run(SourceFile:573)
2013-05-11 21:29:23 [INFO] Creepophile[/68.192.218.229:55790] logged in with entity id 8681312 at ([world] -226.21700569304517, 15.0, 6948.122197562642)
2013-05-11 21:29:28 [INFO] [TownyChat] onPlayerChat: Processing directed message for staff
2013-05-11 21:29:28 [INFO] [Survival][SC][Staff]~Denn: isn't that kinda cheating