Hopper: java.lang.NullPointerException

java.lang.NullPointerException
	at avj.a(SourceFile:26)
	at avi.c(SourceFile:59)
	at arf.g(SourceFile:170)
	at arf.a(SourceFile:193)
	at act.a(SourceFile:1510)
	at oc.J(SourceFile:736)
	at oc.z(SourceFile:339)
	at ou.z(SourceFile:167)
	at ov.z(SourceFile:128)
	at st.z(SourceFile:53)
	at oc.o_(SourceFile:279)
	at ou.o_(SourceFile:1167)
	at ov.o_(SourceFile:169)
	at act.a(SourceFile:1365)
	at kd.a(SourceFile:479)
	at act.g(SourceFile:1343)

---- Minecraft Crash Report ----
// Everything's going to plan. No, really, that was supposed to happen.

Time: 06/09/13 08:58 PM
Description: Ticking entity

java.lang.NullPointerException
	at avj.a(SourceFile:26)
	at avi.c(SourceFile:59)
	at arf.g(SourceFile:170)
	at arf.a(SourceFile:193)
	at act.a(SourceFile:1510)
	at oc.J(SourceFile:736)
	at oc.z(SourceFile:339)
	at ou.z(SourceFile:167)
	at ov.z(SourceFile:128)
	at st.z(SourceFile:53)
	at oc.o_(SourceFile:279)
	at ou.o_(SourceFile:1167)
	at ov.o_(SourceFile:169)
	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 avj.a(SourceFile:26)
	at avi.c(SourceFile:59)
	at arf.g(SourceFile:170)
	at arf.a(SourceFile:193)
	at act.a(SourceFile:1510)
	at oc.J(SourceFile:736)
	at oc.z(SourceFile:339)
	at ou.z(SourceFile:167)
	at ov.z(SourceFile:128)
	at st.z(SourceFile:53)
	at oc.o_(SourceFile:279)
	at ou.o_(SourceFile:1167)
	at ov.o_(SourceFile:169)
	at act.a(SourceFile:1365)
	at kd.a(SourceFile:479)
	at act.g(SourceFile:1343)

-- Entity being ticked --
Details:
	Entity Type: Squid (sr)
	Entity ID: 16965
	Entity Name: Squid
	Entity's Exact location: -20,55, 47,42, 298,43
	Entity's Block location: World: (-21,47,298), Chunk: (at 11,2,10 in -2,18; contains blocks -32,0,288 to -17,255,303), Region: (-1,0; contains chunks -32,0 to -1,31, blocks -512,0,0 to -1,255,511)
	Entity's Momentum: 0,00, -0,03, 0,00
Stacktrace:
	at act.h(SourceFile:1250)
	at kd.h(SourceFile:364)

-- Affected level --
Details:
	Level name: snapshot 1_7
	All players: 1 total; [kg['Joflox_Alpha'/161, l='snapshot 1_7', x=-34,67, y=63,00, z=283,25]]
	Chunk stats: ServerChunkCache: 561 Drop: 0
	Level seed: -582103092
	Level generator: ID 00 - default, ver 1. Features enabled: true
	Level generator options: 
	Level spawn location: World: (16,64,256), Chunk: (at 0,4,0 in 1,16; contains blocks 16,0,256 to 31,255,271), Region: (0,0; contains chunks 0,0 to 31,31, blocks 0,0,0 to 511,255,511)
	Level time: 17846 game time, 1703 day time
	Level dimension: 0
	Level storage version: 0x04ABD - Anvil
	Level weather: Rain time: 93570 (now: false), thunder time: 96252 (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: Windows 7 (x86) version 6.1
	Java Version: 1.7.0_25, Oracle Corporation
	Java VM Version: Java HotSpot(TM) Client VM (mixed mode), Oracle Corporation
	Memory: 630485248 bytes (601 MB) / 1037959168 bytes (989 MB) up to 1037959168 bytes (989 MB)
	JVM Flags: 3 total; -XX:HeapDumpPath=MojangTricksIntelDriversForPerformance_javaw.exe_minecraft.exe.heapdump -Xmx1G -Xms1G
	AABB Pool Size: 3485 (195160 bytes; 0 MB) allocated, 1496 (83776 bytes; 0 MB) used
	IntCache: cache: 0, tcache: 0, allocated: 12, tallocated: 94
	Profiler Position: N/A (disabled)
	Vec3 Pool Size: 2150 (120400 bytes; 0 MB) allocated, 1027 (57512 bytes; 0 MB) used
	Player Count: 1 / 8; [kg['Joflox_Alpha'/161, l='snapshot 1_7', x=-34,67, y=63,00, z=283,25]]
	Type: Integrated Server (map_client.txt)
	Is Modded: Probably not. Jar signature remains and both client + server brands are untouched.