Hopper: java.lang.NullPointerException

This is an automatically generated report based from the following crash: http://hopper.minecraft.net/crashes/minecraft/MCX-196491/

Crash:

java.lang.NullPointerException
	at afm.a(SourceFile:57)
	at afk.a(SourceFile:423)
	at ade.d(SourceFile:309)
	at ade.b(SourceFile:400)
	at ask.a(SourceFile:116)

The following is the first clean report made public about this crash:

---- Minecraft Crash Report ----
// Would you like a cupcake?

Time: 20.9.2013 17:03
Description: Exception while updating neighbours

java.lang.NullPointerException
	at afm.a(SourceFile:57)
	at afk.a(SourceFile:423)
	at ade.d(SourceFile:309)
	at ade.b(SourceFile:400)
	at ask.a(SourceFile:116)
	at ade.e(SourceFile:462)
	at ade.d(SourceFile:440)
	at ade.c(SourceFile:410)
	at ade.d(SourceFile:319)
	at ade.f(SourceFile:372)
	at kr.d(SourceFile:173)
	at kr.b(SourceFile:198)
	at kr.a(SourceFile:110)
	at kv.a(SourceFile:326)
	at gu.a(SourceFile:46)
	at eb.b(SourceFile:63)
	at kv.e(SourceFile:64)
	at ky.b(SourceFile:37)
	at bow.b(SourceFile:83)
	at net.minecraft.server.MinecraftServer.u(SourceFile:487)
	at net.minecraft.server.MinecraftServer.t(SourceFile:404)
	at bot.t(SourceFile:124)
	at net.minecraft.server.MinecraftServer.run(SourceFile:338)
	at jc.run(SourceFile:581)


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

-- Head --
Stacktrace:
	at afm.a(SourceFile:57)
	at afk.a(SourceFile:423)
	at ade.d(SourceFile:309)
	at ade.b(SourceFile:400)
	at ask.a(SourceFile:116)

-- Block being updated --
Details:
	Source block type: ID #90 (tile.portal // ask)
	Block type: ID #90 (tile.portal // ask)
	Block data value: 1 / 0x1 / 0b0001
	Block location: World: (5898,72,43131), Chunk: (at 10,4,11 in 368,2695; contains blocks 5888,0,43120 to 5903,255,43135), Region: (11,84; contains chunks 352,2688 to 383,2719, blocks 5632,0,43008 to 6143,255,43519)
Stacktrace:
	at ade.e(SourceFile:462)
	at ade.d(SourceFile:440)
	at ade.c(SourceFile:410)
	at ade.d(SourceFile:319)
	at ade.f(SourceFile:372)
	at kr.d(SourceFile:173)
	at kr.b(SourceFile:198)
	at kr.a(SourceFile:110)
	at kv.a(SourceFile:326)
	at gu.a(SourceFile:46)
	at eb.b(SourceFile:63)
	at kv.e(SourceFile:64)

-- Ticking connection --
Details:
	Connection: kv@751e342e
Stacktrace:
	at ky.b(SourceFile:37)
	at bow.b(SourceFile:83)
	at net.minecraft.server.MinecraftServer.u(SourceFile:487)
	at net.minecraft.server.MinecraftServer.t(SourceFile:404)
	at bot.t(SourceFile:124)
	at net.minecraft.server.MinecraftServer.run(SourceFile:338)
	at jc.run(SourceFile:581)

-- System Details --
Details:
	Minecraft Version: 13w38b
	Operating System: Windows 7 (amd64) version 6.1
	Java Version: 1.7.0_25, Oracle Corporation
	Java VM Version: Java HotSpot(TM) 64-Bit Server VM (mixed mode), Oracle Corporation
	Memory: 118894168 bytes (113 MB) / 379781120 bytes (362 MB) up to 954466304 bytes (910 MB)
	JVM Flags: 2 total; -XX:HeapDumpPath=MojangTricksIntelDriversForPerformance_javaw.exe_minecraft.exe.heapdump -Xmx1G
	AABB Pool Size: 8084 (452704 bytes; 0 MB) allocated, 7275 (407400 bytes; 0 MB) used
	IntCache: cache: 0, tcache: 0, allocated: 12, tallocated: 94
	Profiler Position: N/A (disabled)
	Vec3 Pool Size: 1665 (93240 bytes; 0 MB) allocated, 1634 (91504 bytes; 0 MB) used
	Player Count: 1 / 8; [kq['McPlayer96'/193, l='New Worldaaa', x=5899,00, y=71,00, z=43132,00]]
	Type: Integrated Server (map_client.txt)
	Is Modded: Probably not. Jar signature remains and both client + server brands are untouched.

You can see this full report at http://hopper.minecraft.net/crashes/minecraft/MCX-196491/12593774/