Hopper: java.lang.IllegalArgumentException: Modifier name cannot be empty

This is an automatically generated report based from the following crash: http://hopper.minecraft.net/crashes/minecraft/MCX-83416/

Crash:

java.lang.IllegalArgumentException: Modifier name cannot be empty
	at org.apache.commons.lang3.Validate.notEmpty(Validate.java:398)
	at pi.<init>(SourceFile:31)
	at ug.a(SourceFile:92)
	at yx.D(SourceFile:581)
	at ou.o_(SourceFile:1188)
	at uw.o_(SourceFile:204)

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

---- Minecraft Crash Report ----
// Oops.

Time: 9/6/13 5:43 AM
Description: Ticking player

java.lang.IllegalArgumentException: Modifier name cannot be empty
	at org.apache.commons.lang3.Validate.notEmpty(Validate.java:398)
	at pi.<init>(SourceFile:31)
	at ug.a(SourceFile:92)
	at yx.D(SourceFile:581)
	at ou.o_(SourceFile:1188)
	at uw.o_(SourceFile:204)
	at kg.h(SourceFile:192)
	at kl.a(SourceFile:195)
	at fd.a(SourceFile:136)
	at cv.b(SourceFile:64)
	at kl.e(SourceFile:63)
	at ko.b(SourceFile:37)
	at bnq.b(SourceFile:84)
	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 org.apache.commons.lang3.Validate.notEmpty(Validate.java:398)
	at pi.<init>(SourceFile:31)
	at ug.a(SourceFile:92)
	at yx.D(SourceFile:581)
	at ou.o_(SourceFile:1188)
	at uw.o_(SourceFile:204)

-- Player being ticked --
Details:
	Entity Type: null (kg)
	Entity ID: 253
	Entity Name: Zemat_Racso
	Entity's Exact location: 926.43, 5.00, -1150.24
	Entity's Block location: World: (926,5,-1151), Chunk: (at 14,0,1 in 57,-72; contains blocks 912,0,-1152 to 927,255,-1137), Region: (1,-3; contains chunks 32,-96 to 63,-65, blocks 512,0,-1536 to 1023,255,-1025)
	Entity's Momentum: 0.00, -0.08, 0.00
Stacktrace:
	at kg.h(SourceFile:192)
	at kl.a(SourceFile:195)
	at fd.a(SourceFile:136)
	at cv.b(SourceFile:64)
	at kl.e(SourceFile:63)

-- Ticking connection --
Details:
	Connection: kl@1c192c8
Stacktrace:
	at ko.b(SourceFile:37)
	at bnq.b(SourceFile:84)
	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 8 (x86) version 6.2
	Java Version: 1.7.0_25, Oracle Corporation
	Java VM Version: Java HotSpot(TM) Client VM (mixed mode), Oracle Corporation
	Memory: 133401344 bytes (127 MB) / 292233216 bytes (278 MB) up to 1037959168 bytes (989 MB)
	JVM Flags: 2 total; -XX:HeapDumpPath=MojangTricksIntelDriversForPerformance_javaw.exe_minecraft.exe.heapdump -Xmx1G
	AABB Pool Size: 4692 (262752 bytes; 0 MB) allocated, 4406 (246736 bytes; 0 MB) used
	IntCache: cache: 0, tcache: 0, allocated: 0, tallocated: 0
	Profiler Position: N/A (disabled)
	Vec3 Pool Size: 568 (31808 bytes; 0 MB) allocated, 530 (29680 bytes; 0 MB) used
	Player Count: 1 / 8; [kg['Zemat_Racso'/253, l='MCEdit', x=926.43, y=5.00, z=-1150.24]]
	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-83416/8316517/