2014-01-21 20:31:20 [SEVERE] "Silently" catching entity tracking error.
2014-01-21 20:31:20 [SEVERE] net.minecraft.util.ReportedException: Adding entity to track
2014-01-21 20:31:20 [SEVERE]    at net.minecraft.entity.EntityTracker.func_72785_a(EntityTracker.java:226)
2014-01-21 20:31:20 [SEVERE]    at cpw.mods.fml.common.registry.EntityRegistry.tryTrackingEntity(EntityRegistry.java:400)
2014-01-21 20:31:20 [SEVERE]    at net.minecraft.entity.EntityTracker.func_72786_a(EntityTracker.java:64)
2014-01-21 20:31:20 [SEVERE]    at net.minecraft.world.WorldManager.func_72703_a(WorldManager.java:37)
2014-01-21 20:31:20 [SEVERE]    at net.minecraft.world.World.func_72923_a(World.java:1978)
2014-01-21 20:31:20 [SEVERE]    at net.minecraft.world.WorldServer.func_72923_a(WorldServer.java:1292)
2014-01-21 20:31:20 [SEVERE]    at net.minecraft.world.World.func_72868_a(World.java:4380)
2014-01-21 20:31:20 [SEVERE]    at net.minecraft.world.chunk.Chunk.func_76631_c(Chunk.java:1154)
2014-01-21 20:31:20 [SEVERE]    at org.bukkit.craftbukkit.v1_6_R3.chunkio.ChunkIOProvider.callStage2(ChunkIOProvider.java:54)
2014-01-21 20:31:20 [SEVERE]    at org.bukkit.craftbukkit.v1_6_R3.chunkio.ChunkIOProvider.callStage2(ChunkIOProvider.java:15)
2014-01-21 20:31:20 [SEVERE]    at org.bukkit.craftbukkit.v1_6_R3.util.AsynchronousExecutor$Task.finish(AsynchronousExecutor.java:179)
2014-01-21 20:31:20 [SEVERE]    at org.bukkit.craftbukkit.v1_6_R3.util.AsynchronousExecutor.finishActive(AsynchronousExecutor.java:287)
2014-01-21 20:31:20 [SEVERE]    at org.bukkit.craftbukkit.v1_6_R3.chunkio.ChunkIOExecutor.tick(ChunkIOExecutor.java:26)
2014-01-21 20:31:20 [SEVERE]    at net.minecraft.server.MinecraftServer.func_71190_q(MinecraftServer.java:836)
2014-01-21 20:31:20 [SEVERE]    at net.minecraft.server.dedicated.DedicatedServer.func_71190_q(DedicatedServer.java:330)
2014-01-21 20:31:20 [SEVERE]    at net.minecraft.server.MinecraftServer.func_71217_p(MinecraftServer.java:781)
2014-01-21 20:31:20 [SEVERE]    at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:663)
2014-01-21 20:31:20 [SEVERE]    at net.minecraft.server.ThreadMinecraftServer.run(ThreadMinecraftServer.java:16)
2014-01-21 20:31:20 [SEVERE] Caused by: java.lang.IllegalStateException: Entity is already tracked!
2014-01-21 20:31:20 [SEVERE]    at net.minecraft.entity.EntityTracker.func_72785_a(EntityTracker.java:206)
2014-01-21 20:31:20 [SEVERE]    ... 17 more