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 act.g(SourceFile:1343)

---- Minecraft Crash Report ----
// This doesn't make any sense!

Time: 9/7/13 10:40 AM
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 act.g(SourceFile:1343)
	at act.h(SourceFile:1250)
	at awb.m(SourceFile:1426)
	at awb.V(SourceFile:686)
	at awb.e(SourceFile:642)
	at net.minecraft.client.main.Main.main(SourceFile:103)


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 act.g(SourceFile:1343)

-- Entity being ticked --
Details:
	Entity Type: Bat (sd)
	Entity ID: 205
	Entity Name: Bat
	Entity's Exact location: 494.50, 76.00, 8.50
	Entity's Block location: World: (494,76,8), Chunk: (at 14,4,8 in 30,0; contains blocks 480,0,0 to 495,255,15), Region: (0,0; contains chunks 0,0 to 31,31, blocks 0,0,0 to 511,255,511)
	Entity's Momentum: 0.00, 0.00, 0.00
Stacktrace:
	at act.h(SourceFile:1250)

-- Affected level --
Details:
	Level name: MpServer
	All players: 1 total; [bfn['Addgame'/8, l='MpServer', x=495.41, y=59.79, z=9.01]]
	Chunk stats: MultiplayerChunkCache: 225, 225
	Level seed: 0
	Level generator: ID 01 - flat, ver 0. Features enabled: false
	Level generator options: 
	Level spawn location: World: (516,4,21), Chunk: (at 4,0,5 in 32,1; contains blocks 512,0,16 to 527,255,31), Region: (1,0; contains chunks 32,0 to 63,31, blocks 512,0,0 to 1023,255,511)
	Level time: 3798679 game time, 6000 day time
	Level dimension: 0
	Level storage version: 0x00000 - Unknown?
	Level weather: Rain time: 0 (now: false), thunder time: 0 (now: false)
	Level game mode: Game mode: creative (ID 1). Hardcore: false. Cheats: false
	Forced entities: 11 total; [sd['Bat'/205, l='MpServer', x=494.50, y=76.00, z=8.50], uk['Spider'/0, l='MpServer', x=487.47, y=56.00, z=3.92], sn['Dinnerbone'/204, l='MpServer', x=494.50, y=76.00, z=8.50], sh['Horse'/1, l='MpServer', x=551.59, y=56.00, z=46.78], tq['entity.MinecartSpawner.name'/2, l='MpServer', x=565.50, y=58.34, z=73.50], tq['entity.MinecartSpawner.name'/3, l='MpServer', x=565.50, y=58.34, z=76.50], tq['entity.MinecartSpawner.name'/4, l='MpServer', x=565.50, y=58.34, z=70.50], tq['entity.MinecartSpawner.name'/5, l='MpServer', x=565.50, y=58.34, z=79.50], tt['Block of TNT'/203, l='MpServer', x=494.50, y=76.43, z=8.50], ot['entity.LeashKnot.name'/7, l='MpServer', x=553.50, y=56.50, z=46.50], bfn['Addgame'/8, l='MpServer', x=495.41, y=59.79, z=9.01]]
	Retry entities: 0 total; []
	Server brand: vanilla
	Server type: Integrated singleplayer server
Stacktrace:
	at bfi.a(SourceFile:285)
	at awb.b(SourceFile:1813)
	at awb.e(SourceFile:651)
	at net.minecraft.client.main.Main.main(SourceFile:103)

-- System Details --
Details:
	Minecraft Version: 13w36b
	Operating System: Windows 8 (amd64) version 6.2
	Java Version: 1.7.0_25, Oracle Corporation
	Java VM Version: Java HotSpot(TM) 64-Bit Server VM (mixed mode), Oracle Corporation
	Memory: 70492968 bytes (67 MB) / 355991552 bytes (339 MB) up to 954466304 bytes (910 MB)
	JVM Flags: 2 total; -XX:HeapDumpPath=MojangTricksIntelDriversForPerformance_javaw.exe_minecraft.exe.heapdump -Xmx1G
	AABB Pool Size: 15971 (894376 bytes; 0 MB) allocated, 74 (4144 bytes; 0 MB) used
	IntCache: cache: 0, tcache: 0, allocated: 0, tallocated: 0
	Launched Version: 13w36b
	LWJGL: 2.9.0
	OpenGL: Intel(R) HD Graphics 4000 GL version 4.0.0 - Build 9.17.10.2828, Intel
	Is Modded: Probably not. Jar signature remains and client brand is untouched.
	Type: Client (map_client.txt)
	Resource Packs: []
	Current Language: English (US)
	Profiler Position: N/A (disabled)
	Vec3 Pool Size: 79 (4424 bytes; 0 MB) allocated, 21 (1176 bytes; 0 MB) used