Hopper: java.lang.ArrayIndexOutOfBoundsException: 6

This is an automatically generated report based from the following crash: http://hopper.minecraft.net/crashes/minecraft/MCX-465487/

Crash:

java.lang.ArrayIndexOutOfBoundsException: 6
	at aob.h(SourceFile:381)
	at aob.e(SourceFile:142)
	at aob.a(SourceFile:120)

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

---- Minecraft Crash Report ----
// I'm sorry, Dave.

Time: 13.25.10 19:24
Description: Exception while updating neighbours

java.lang.ArrayIndexOutOfBoundsException: 6
	at aob.h(SourceFile:381)
	at aob.e(SourceFile:142)
	at aob.a(SourceFile:120)
	at afn.e(SourceFile:480)
	at afn.d(SourceFile:461)
	at aie.a(SourceFile:294)
	at aie.a(SourceFile:175)
	at mn.a(SourceFile:241)
	at mx.a(SourceFile:365)
	at jc.a(SourceFile:60)
	at jc.a(SourceFile:9)
	at ef.a(SourceFile:164)
	at ms.c(SourceFile:134)
	at net.minecraft.server.MinecraftServer.u(SourceFile:529)
	at net.minecraft.server.MinecraftServer.t(SourceFile:441)
	at bsk.t(SourceFile:117)
	at net.minecraft.server.MinecraftServer.run(SourceFile:358)
	at ky.run(SourceFile:617)


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

-- Head --
Stacktrace:
	at aob.h(SourceFile:381)
	at aob.e(SourceFile:142)
	at aob.a(SourceFile:120)

-- Block being updated --
Details:
	Source block type: ID #77 (tile.button // amj)
	Block type: ID #33 (tile.pistonBase // aob)
	Block data value: 6 / 0x6 / 0b0110
	Block location: World: (-7,238,-7), Chunk: (at 9,14,9 in -1,-1; contains blocks -16,0,-16 to -1,255,-1), Region: (-1,-1; contains chunks -32,-32 to -1,-1, blocks -512,0,-512 to -1,255,-1)
Stacktrace:
	at afn.e(SourceFile:480)
	at afn.d(SourceFile:461)
	at aie.a(SourceFile:294)
	at aie.a(SourceFile:175)
	at mn.a(SourceFile:241)
	at mx.a(SourceFile:365)
	at jc.a(SourceFile:60)
	at jc.a(SourceFile:9)
	at ef.a(SourceFile:164)

-- Ticking connection --
Details:
	Connection: ef@1da298d
Stacktrace:
	at ms.c(SourceFile:134)
	at net.minecraft.server.MinecraftServer.u(SourceFile:529)
	at net.minecraft.server.MinecraftServer.t(SourceFile:441)
	at bsk.t(SourceFile:117)
	at net.minecraft.server.MinecraftServer.run(SourceFile:358)
	at ky.run(SourceFile:617)

-- System Details --
Details:
	Minecraft Version: 1.7.2
	Operating System: Windows 8 (x86) version 6.2
	Java Version: 1.7.0_45, Oracle Corporation
	Java VM Version: Java HotSpot(TM) Client VM (mixed mode, sharing), Oracle Corporation
	Memory: 188153352 bytes (179 MB) / 518979584 bytes (494 MB) up to 518979584 bytes (494 MB)
	JVM Flags: 2 total; -XX:HeapDumpPath=MojangTricksIntelDriversForPerformance_javaw.exe_minecraft.exe.heapdump -Xmx512M
	AABB Pool Size: 472 (26432 bytes; 0 MB) allocated, 186 (10416 bytes; 0 MB) used
	IntCache: cache: 0, tcache: 0, allocated: 13, tallocated: 95
	Profiler Position: N/A (disabled)
	Vec3 Pool Size: 36 (2016 bytes; 0 MB) allocated, 24 (1344 bytes; 0 MB) used
	Player Count: 1 / 8; [mm['arturspujats'/66946, l='Minecraft Fun and Command Block', x=-6,75, y=237,00, z=-4,56]]
	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-465487/21405588/