A minecraft crash

---- Minecraft Crash Report ----
// Shall we play a game?

Time: 6/8/13 11:20 PM
Description: Sending packet

java.lang.NullPointerException
	at cl.b(SourceFile:116)
	at cl.a(SourceFile:41)
	at jo.b(SourceFile:430)
	at hb.b(SourceFile:644)
	at hb.a(SourceFile:79)
	at bit.b(SourceFile:73)
	at net.minecraft.server.MinecraftServer.s(SourceFile:491)
	at net.minecraft.server.MinecraftServer.r(SourceFile:408)
	at biq.r(SourceFile:125)
	at net.minecraft.server.MinecraftServer.run(SourceFile:342)
	at gw.run(SourceFile:585)


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

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

-- Packet being sent --
Details:
	Packet ID: 4
	Packet class: fn
Stacktrace:
	at jo.b(SourceFile:430)
	at hb.b(SourceFile:644)
	at hb.a(SourceFile:79)
	at bit.b(SourceFile:73)
	at net.minecraft.server.MinecraftServer.s(SourceFile:491)
	at net.minecraft.server.MinecraftServer.r(SourceFile:408)
	at biq.r(SourceFile:125)
	at net.minecraft.server.MinecraftServer.run(SourceFile:342)
	at gw.run(SourceFile:585)

-- System Details --
Details:
	Minecraft Version: 13w23b
	Operating System: Windows 7 (x86) version 6.1
	Java Version: 1.7.0_05, Oracle Corporation
	Java VM Version: Java HotSpot(TM) Client VM (mixed mode), Oracle Corporation
	Memory: 526848880 bytes (502 MB) / 1037959168 bytes (989 MB) up to 1037959168 bytes (989 MB)
	JVM Flags: 1 total; -Xmx1G
	AABB Pool Size: 6701 (375256 bytes; 0 MB) allocated, 6701 (375256 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: 5720 (320320 bytes; 0 MB) allocated, 5720 (320320 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.