Hopper: java.lang.NullPointerException 13w36b

This is an automatically generated report based from the following crash: http://hopper.minecraft.net/crashes/minecraft/MCX-83851/

Crash:

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

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

---- Minecraft Crash Report ----
// Why is it breaking :(

Time: 9/6/13 9:58 PM
Description: Sending packet

java.lang.NullPointerException
	at cv.b(SourceFile:116)
	at cv.a(SourceFile:41)
	at kl.b(SourceFile:430)
	at le.b(SourceFile:170)
	at hw.a(SourceFile:86)
	at bnq.b(SourceFile:73)
	at net.minecraft.server.MinecraftServer.t(SourceFile:481)
	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 cv.b(SourceFile:116)
	at cv.a(SourceFile:41)

-- Packet being sent --
Details:
	Packet ID: 200
	Packet class: dt
Stacktrace:
	at kl.b(SourceFile:430)
	at le.b(SourceFile:170)
	at hw.a(SourceFile:86)
	at bnq.b(SourceFile:73)
	at net.minecraft.server.MinecraftServer.t(SourceFile:481)
	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: 126205288 bytes (120 MB) / 207777792 bytes (198 MB) up to 1037959168 bytes (989 MB)
	JVM Flags: 2 total; -XX:HeapDumpPath=MojangTricksIntelDriversForPerformance_javaw.exe_minecraft.exe.heapdump -Xmx1G
	AABB Pool Size: 786 (44016 bytes; 0 MB) allocated, 786 (44016 bytes; 0 MB) used
	IntCache: cache: 0, tcache: 0, allocated: 13, tallocated: 95
	Profiler Position: N/A (disabled)
	Vec3 Pool Size: 102 (5712 bytes; 0 MB) allocated, 102 (5712 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-83851/8332008/