Hopper: java.lang.NullPointerException 1.6.1 cm.b(SourceFile:116)

This is an automatically generated report based from the following crash: http://hopper.minecraft.net/crashes/minecraft/MCX-1964/

Crash:

java.lang.NullPointerException
	at cm.b(SourceFile:116)
	at cm.a(SourceFile:41)

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

---- Minecraft Crash Report ----
// I bet Cylons wouldn't have this problem.

Time: 03.08.13 09:25
Description: Sending packet

java.lang.NullPointerException
	at cm.b(SourceFile:116)
	at cm.a(SourceFile:41)
	at jx.b(SourceFile:436)
	at hk.b(SourceFile:644)
	at hk.a(SourceFile:79)
	at bkr.b(SourceFile:73)
	at net.minecraft.server.MinecraftServer.t(SourceFile:488)
	at net.minecraft.server.MinecraftServer.s(SourceFile:405)
	at bko.s(SourceFile:124)
	at net.minecraft.server.MinecraftServer.run(SourceFile:339)
	at hf.run(SourceFile:582)


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

-- Head --
Stacktrace:
	at cm.b(SourceFile:116)
	at cm.a(SourceFile:41)

-- Packet being sent --
Details:
	Packet ID: 4
	Packet class: fw
Stacktrace:
	at jx.b(SourceFile:436)
	at hk.b(SourceFile:644)
	at hk.a(SourceFile:79)
	at bkr.b(SourceFile:73)
	at net.minecraft.server.MinecraftServer.t(SourceFile:488)
	at net.minecraft.server.MinecraftServer.s(SourceFile:405)
	at bko.s(SourceFile:124)
	at net.minecraft.server.MinecraftServer.run(SourceFile:339)
	at hf.run(SourceFile:582)

-- System Details --
Details:
	Minecraft Version: 1.6.1
	Operating System: Windows 8 (amd64) version 6.2
	Java Version: 1.7.0_21, Oracle Corporation
	Java VM Version: Java HotSpot(TM) 64-Bit Server VM (mixed mode), Oracle Corporation
	Memory: 85143416 bytes (81 MB) / 157810688 bytes (150 MB) up to 954466304 bytes (910 MB)
	JVM Flags: 2 total; -XX:HeapDumpPath=MojangTricksIntelDriversForPerformance_javaw.exe_minecraft.exe.heapdump -Xmx1G
	AABB Pool Size: 2065 (115640 bytes; 0 MB) allocated, 2065 (115640 bytes; 0 MB) used
	Suspicious classes: No suspicious classes found.
	IntCache: cache: 0, tcache: 0, allocated: 1, tallocated: 63
	Profiler Position: N/A (disabled)
	Vec3 Pool Size: 1072 (60032 bytes; 0 MB) allocated, 1072 (60032 bytes; 0 MB) used
	Player Count: 0 / 8; []
	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-1964/202186/