i don't know

---- Minecraft Crash Report ----
// I just don't know what went wrong :(

Time: 4.6.2013 10:28
Description: Loading entity NBT

java.lang.NullPointerException
	at np.a(SourceFile:357)
	at tk.a(SourceFile:580)
	at jh.a(SourceFile:81)
	at mx.f(SourceFile:1061)
	at gz.a(SourceFile:152)
	at gz.a(SourceFile:52)
	at bik.b(SourceFile:73)
	at net.minecraft.server.MinecraftServer.s(SourceFile:491)
	at net.minecraft.server.MinecraftServer.r(SourceFile:408)
	at bih.r(SourceFile:125)
	at net.minecraft.server.MinecraftServer.run(SourceFile:342)
	at gu.run(SourceFile:585)


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

-- Head --
Stacktrace:
	at np.a(SourceFile:357)
	at tk.a(SourceFile:580)
	at jh.a(SourceFile:81)

-- Entity being loaded --
Details:
	Entity Type: null (jh)
	Entity ID: 174312
	Entity Name: ihmismies12
	Entity's Exact location: -443,24, 63,00, 261,86
	Entity's Block location: World: (-444,63,261), Chunk: (at 4,3,5 in -28,16; contains blocks -448,0,256 to -433,255,271), Region: (-1,0; contains chunks -32,0 to -1,31, blocks -512,0,0 to -1,255,511)
	Entity's Momentum: 0,00, -0,08, 0,00
Stacktrace:
	at mx.f(SourceFile:1061)
	at gz.a(SourceFile:152)
	at gz.a(SourceFile:52)
	at bik.b(SourceFile:73)
	at net.minecraft.server.MinecraftServer.s(SourceFile:491)
	at net.minecraft.server.MinecraftServer.r(SourceFile:408)
	at bih.r(SourceFile:125)
	at net.minecraft.server.MinecraftServer.run(SourceFile:342)
	at gu.run(SourceFile:585)

-- System Details --
Details:
	Minecraft Version: 13w22a
	Operating System: Windows 7 (x86) version 6.1
	Java Version: 1.7.0_21, Oracle Corporation
	Java VM Version: Java HotSpot(TM) Client VM (mixed mode), Oracle Corporation
	Memory: 127706928 bytes (121 MB) / 418086912 bytes (398 MB) up to 1037959168 bytes (989 MB)
	JVM Flags: 1 total; -Xmx1G
	AABB Pool Size: 88 (4928 bytes; 0 MB) allocated, 88 (4928 bytes; 0 MB) used
	Suspicious classes: No suspicious classes found.
	IntCache: cache: 0, tcache: 0, allocated: 0, tallocated: 0
	Profiler Position: N/A (disabled)
	Vec3 Pool Size: 12 (672 bytes; 0 MB) allocated, 12 (672 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