Crash

---- Minecraft Crash Report ----
// Hey, that tickles! Hehehe!

Time: 17.07.14 1:36
Description: Ticking entity

java.lang.IllegalArgumentException: Cannot get property bcy{name=half, clazz=class ats, values=[upper, lower]} as it does not exist in bch{block=minecraft:air, properties=[]}
	at bck.b(SourceFile:112)
	at atr.a(SourceFile:147)
	at zi.d(SourceFile:29)
	at yr.a(SourceFile:87)
	at xb.bD(SourceFile:457)
	at xa.l(SourceFile:1431)
	at xb.l(SourceFile:327)
	at wd.l(SourceFile:126)
	at xa.j(SourceFile:1299)
	at xb.j(SourceFile:206)
	at apo.a(SourceFile:1414)
	at qi.a(SourceFile:569)
	at apo.g(SourceFile:1392)
	at apo.i(SourceFile:1286)
	at qi.i(SourceFile:447)
	at net.minecraft.server.MinecraftServer.x(SourceFile:586)
	at net.minecraft.server.MinecraftServer.w(SourceFile:510)
	at cvl.w(SourceFile:132)
	at net.minecraft.server.MinecraftServer.run(SourceFile:426)
	at java.lang.Thread.run(Unknown Source)