2013-01-27 13:03:18 [SEVERE] net.minecraft.server.v1_4_6.ReportedException: Exception ticking world
2013-01-27 13:03:18 [SEVERE] 	at net.minecraft.server.v1_4_6.MinecraftServer.r(MinecraftServer.java:563)
2013-01-27 13:03:18 [SEVERE] 	at net.minecraft.server.v1_4_6.DedicatedServer.r(DedicatedServer.java:224)
2013-01-27 13:03:18 [SEVERE] 	at net.minecraft.server.v1_4_6.MinecraftServer.q(MinecraftServer.java:481)
2013-01-27 13:03:18 [SEVERE] 	at net.minecraft.server.v1_4_6.MinecraftServer.run(MinecraftServer.java:416)
2013-01-27 13:03:18 [SEVERE] 	at net.minecraft.server.v1_4_6.ThreadServerApplication.run(SourceFile:849)
2013-01-27 13:03:18 [SEVERE] Caused by: java.lang.NullPointerException
2013-01-27 13:03:18 [SEVERE] 	at net.minecraft.server.v1_4_6.World.a(World.java:2546)
2013-01-27 13:03:18 [SEVERE] 	at net.minecraft.server.v1_4_6.SpawnerCreature.spawnEntities(SpawnerCreature.java:106)
2013-01-27 13:03:18 [SEVERE] 	at net.minecraft.server.v1_4_6.WorldServer.doTick(WorldServer.java:160)
2013-01-27 13:03:18 [SEVERE] 	at net.minecraft.server.v1_4_6.MinecraftServer.r(MinecraftServer.java:559)
2013-01-27 13:03:18 [SEVERE] 	... 4 more
2013-01-27 13:03:18 [SEVERE] Encountered an unexpected exception ReportedException
net.minecraft.server.v1_4_6.ReportedException: Exception ticking world
	at net.minecraft.server.v1_4_6.MinecraftServer.r(MinecraftServer.java:563)
	at net.minecraft.server.v1_4_6.DedicatedServer.r(DedicatedServer.java:224)
	at net.minecraft.server.v1_4_6.MinecraftServer.q(MinecraftServer.java:481)
	at net.minecraft.server.v1_4_6.MinecraftServer.run(MinecraftServer.java:416)
	at net.minecraft.server.v1_4_6.ThreadServerApplication.run(SourceFile:849)
Caused by: java.lang.NullPointerException
	at net.minecraft.server.v1_4_6.World.a(World.java:2546)
	at net.minecraft.server.v1_4_6.SpawnerCreature.spawnEntities(SpawnerCreature.java:106)
	at net.minecraft.server.v1_4_6.WorldServer.doTick(WorldServer.java:160)
	at net.minecraft.server.v1_4_6.MinecraftServer.r(MinecraftServer.java:559)
	... 4 more