Hopper: java.lang.NullPointerException: Handling packet

java.lang.NullPointerException: Handling packet
	at nu.a(SourceFile:539)
	at nv.a(SourceFile:274)
	at of.a(SourceFile:406)
	at kj.a(SourceFile:59)
	at kj.a(SourceFile:10)

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

Time: 30/01/14 16:10
Description: Handling packet

java.lang.NullPointerException: Handling packet
	at nu.a(SourceFile:539)
	at nv.a(SourceFile:274)
	at of.a(SourceFile:406)
	at kj.a(SourceFile:59)
	at kj.a(SourceFile:10)
	at fe.a(SourceFile:163)
	at oa.c(SourceFile:134)
	at net.minecraft.server.MinecraftServer.v(SourceFile:545)
	at net.minecraft.server.MinecraftServer.u(SourceFile:461)
	at bzz.u(SourceFile:123)
	at net.minecraft.server.MinecraftServer.run(SourceFile:377)
	at mh.run(SourceFile:647)


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

-- Head --
Stacktrace:
	at nu.a(SourceFile:539)
	at nv.a(SourceFile:274)
	at of.a(SourceFile:406)
	at kj.a(SourceFile:59)
	at kj.a(SourceFile:10)

-- Packet information --
Details:
	Packet name: kj
	Packet debug: 
Stacktrace:
	at fe.a(SourceFile:163)

-- Ticking connection --
Details:
	Connection: fe@1380924
Stacktrace:
	at oa.c(SourceFile:134)
	at net.minecraft.server.MinecraftServer.v(SourceFile:545)
	at net.minecraft.server.MinecraftServer.u(SourceFile:461)
	at bzz.u(SourceFile:123)
	at net.minecraft.server.MinecraftServer.run(SourceFile:377)
	at mh.run(SourceFile:647)

-- System Details --
Details:
	Minecraft Version: 14w05a
	Operating System: Windows 7 (x86) version 6.1
	Java Version: 1.7.0_51, Oracle Corporation
	Java VM Version: Java HotSpot(TM) Client VM (mixed mode, sharing), Oracle Corporation
	Memory: 103265864 bytes (98 MB) / 518979584 bytes (494 MB) up to 518979584 bytes (494 MB)
	JVM Flags: 2 total; -XX:HeapDumpPath=MojangTricksIntelDriversForPerformance_javaw.exe_minecraft.exe.heapdump -Xmx512M
	IntCache: cache: 0, tcache: 0, allocated: 0, tallocated: 0
	Profiler Position: N/A (disabled)
	Player Count: 1 / 8; [nu['gugamentel'/9, l='A Shopping Survival 2', x=-22,78, y=164,02, z=-110,45]]
	Type: Integrated Server (map_client.txt)
	Is Modded: Probably not. Jar signature remains and both client + server brands are untouched.