Hopper: java.lang.NullPointerException

java.lang.NullPointerException
	at ny.a(SourceFile:89)
	at ou.aL(SourceFile:396)
	at ou.z(SourceFile:222)
	at ov.z(SourceFile:128)
	at oc.o_(SourceFile:279)
	at ou.o_(SourceFile:1167)
	at ov.o_(SourceFile:169)
	at sd.o_(SourceFile:107)
	at act.a(SourceFile:1365)
	at kd.a(SourceFile:479)
	at act.g(SourceFile:1343)

---- Minecraft Crash Report ----
// Daisy, daisy...

Time: 9/6/13 9:46 PM
Description: Ticking entity

java.lang.NullPointerException
	at ny.a(SourceFile:89)
	at ou.aL(SourceFile:396)
	at ou.z(SourceFile:222)
	at ov.z(SourceFile:128)
	at oc.o_(SourceFile:279)
	at ou.o_(SourceFile:1167)
	at ov.o_(SourceFile:169)
	at sd.o_(SourceFile:107)
	at act.a(SourceFile:1365)
	at kd.a(SourceFile:479)
	at act.g(SourceFile:1343)
	at act.h(SourceFile:1250)
	at kd.h(SourceFile:364)
	at net.minecraft.server.MinecraftServer.t(SourceFile:463)
	at net.minecraft.server.MinecraftServer.s(SourceFile:398)
	at bnn.s(SourceFile:124)
	at net.minecraft.server.MinecraftServer.run(SourceFile:332)
	at hr.run(SourceFile:575)


A detailed walkthrough of the error, its code path and all known details is as follows:
---------------------------------------------------------------------------------------

-- Head --
Stacktrace:
	at ny.a(SourceFile:89)
	at ou.aL(SourceFile:396)
	at ou.z(SourceFile:222)
	at ov.z(SourceFile:128)
	at oc.o_(SourceFile:279)
	at ou.o_(SourceFile:1167)
	at ov.o_(SourceFile:169)
	at sd.o_(SourceFile:107)
	at act.a(SourceFile:1365)
	at kd.a(SourceFile:479)
	at act.g(SourceFile:1343)

-- Entity being ticked --
Details:
	Entity Type: Bat (sd)
	Entity ID: 221628
	Entity Name: Bat
	Entity's Exact location: -1432.50, 59.00, 949.50
	Entity's Block location: World: (-1433,59,949), Chunk: (at 7,3,5 in -90,59; contains blocks -1440,0,944 to -1425,255,959), Region: (-3,1; contains chunks -96,32 to -65,63, blocks -1536,0,512 to -1025,255,1023)
	Entity's Momentum: 0.00, 0.00, 0.00
Stacktrace:
	at act.h(SourceFile:1250)
	at kd.h(SourceFile:364)

-- Affected level --
Details:
	Level name: New World
	All players: 1 total; [kg['RyanJRussell'/62, l='New World', x=-1431.94, y=64.00, z=951.41]]
	Chunk stats: ServerChunkCache: 1066 Drop: 0
	Level seed: -4946607663403529650
	Level generator: ID 01 - flat, ver 0. Features enabled: true
	Level generator options: 2;7,59x1,3x3,2;1;stronghold,biome_1,village,decoration,dungeon,lake,mineshaft,lava_lake
	Level spawn location: World: (-232,4,146), Chunk: (at 8,0,2 in -15,9; contains blocks -240,0,144 to -225,255,159), Region: (-1,0; contains chunks -32,0 to -1,31, blocks -512,0,0 to -1,255,511)
	Level time: 133158 game time, 144751 day time
	Level dimension: 0
	Level storage version: 0x04ABD - Anvil
	Level weather: Rain time: 27654 (now: false), thunder time: 22744 (now: false)
	Level game mode: Game mode: creative (ID 1). Hardcore: false. Cheats: true
Stacktrace:
	at net.minecraft.server.MinecraftServer.t(SourceFile:463)
	at net.minecraft.server.MinecraftServer.s(SourceFile:398)
	at bnn.s(SourceFile:124)
	at net.minecraft.server.MinecraftServer.run(SourceFile:332)
	at hr.run(SourceFile:575)

-- System Details --
Details:
	Minecraft Version: 13w36b
	Operating System: Linux (amd64) version 3.2.0-51-generic
	Java Version: 1.6.0_27, Sun Microsystems Inc.
	Java VM Version: OpenJDK 64-Bit Server VM (mixed mode), Sun Microsystems Inc.
	Memory: 49460344 bytes (47 MB) / 386793472 bytes (368 MB) up to 954466304 bytes (910 MB)
	JVM Flags: 1 total; -Xmx1G
	AABB Pool Size: 6688 (374528 bytes; 0 MB) allocated, 5389 (301784 bytes; 0 MB) used
	IntCache: cache: 0, tcache: 0, allocated: 0, tallocated: 0
	Profiler Position: N/A (disabled)
	Vec3 Pool Size: 65602 (3673712 bytes; 3 MB) allocated, 1007 (56392 bytes; 0 MB) used
	Player Count: 1 / 8; [kg['RyanJRussell'/62, l='New World', x=-1431.94, y=64.00, z=951.41]]
	Type: Integrated Server (map_client.txt)
	Is Modded: Probably not. Jar signature remains and both client + server brands are untouched.