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-316111/

Crash:

java.lang.IllegalArgumentException: Modifier name cannot be empty
	at org.apache.commons.lang3.Validate.notEmpty(Validate.java:398)
	at rm.<init>(SourceFile:29)
	at wm.a(SourceFile:94)
	at abg.D(SourceFile:594)
	at qy.h(SourceFile:1190)
	at xc.h(SourceFile:240)

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

---- Minecraft Crash Report ----
// On the bright side, I bought you a teddy bear!

Time: 10/11/13 4:55 PM
Description: Ticking player

java.lang.IllegalArgumentException: Modifier name cannot be empty
	at org.apache.commons.lang3.Validate.notEmpty(Validate.java:398)
	at rm.<init>(SourceFile:29)
	at wm.a(SourceFile:94)
	at abg.D(SourceFile:594)
	at qy.h(SourceFile:1190)
	at xc.h(SourceFile:240)
	at mf.i(SourceFile:207)
	at mp.a(SourceFile:202)
	at ip.a(SourceFile:137)
	at ir.a(SourceFile:20)
	at ek.a(SourceFile:146)
	at ml.c(SourceFile:134)
	at net.minecraft.server.MinecraftServer.u(SourceFile:529)
	at net.minecraft.server.MinecraftServer.t(SourceFile:441)
	at brh.t(SourceFile:117)
	at net.minecraft.server.MinecraftServer.run(SourceFile:358)
	at kt.run(SourceFile:617)


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 rm.<init>(SourceFile:29)
	at wm.a(SourceFile:94)
	at abg.D(SourceFile:594)
	at qy.h(SourceFile:1190)
	at xc.h(SourceFile:240)

-- Player being ticked --
Details:
	Entity Type: null (mf)
	Entity ID: 293
	Entity Name: antvenom098
	Entity's Exact location: -178.31, 64.97, 395.07
	Entity's Block location: World: (-179,64,395), Chunk: (at 13,4,11 in -12,24; contains blocks -192,0,384 to -177,255,399), Region: (-1,0; contains chunks -32,0 to -1,31, blocks -512,0,0 to -1,255,511)
	Entity's Momentum: 0.00, 0.00, 0.00
Stacktrace:
	at mf.i(SourceFile:207)
	at mp.a(SourceFile:202)
	at ip.a(SourceFile:137)
	at ir.a(SourceFile:20)
	at ek.a(SourceFile:146)

-- Ticking connection --
Details:
	Connection: ek@3f9e529
Stacktrace:
	at ml.c(SourceFile:134)
	at net.minecraft.server.MinecraftServer.u(SourceFile:529)
	at net.minecraft.server.MinecraftServer.t(SourceFile:441)
	at brh.t(SourceFile:117)
	at net.minecraft.server.MinecraftServer.run(SourceFile:358)
	at kt.run(SourceFile:617)

-- System Details --
Details:
	Minecraft Version: 13w41b
	Operating System: Mac OS X (x86_64) version 10.7.5
	Java Version: 1.6.0_51, Apple Inc.
	Java VM Version: Java HotSpot(TM) 64-Bit Server VM (mixed mode), Apple Inc.
	Memory: 83999320 bytes (80 MB) / 196886528 bytes (187 MB) up to 1065025536 bytes (1015 MB)
	JVM Flags: 1 total; -Xmx1G
	AABB Pool Size: 4286 (240016 bytes; 0 MB) allocated, 4286 (240016 bytes; 0 MB) used
	IntCache: cache: 0, tcache: 0, allocated: 13, tallocated: 95
	Profiler Position: N/A (disabled)
	Vec3 Pool Size: 7595 (425320 bytes; 0 MB) allocated, 7595 (425320 bytes; 0 MB) used
	Player Count: 1 / 8; [mf['antvenom098'/293, l='Eddison Valley', x=-178.31, y=64.97, z=395.07]]
	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-316111/16934775/