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-449442/

Crash:

java.lang.IllegalArgumentException: Modifier name cannot be empty
	at org.apache.commons.lang3.Validate.notEmpty(Validate.java:398)
	at ru.<init>(SourceFile:29)
	at wu.a(SourceFile:94)
	at abo.D(SourceFile:594)
	at rg.h(SourceFile:1195)
	at xk.h(SourceFile:240)

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

---- Minecraft Crash Report ----
// You should try our sister game, Minceraft!

Time: 10/23/13 5:57 PM
Description: Ticking player

java.lang.IllegalArgumentException: Modifier name cannot be empty
	at org.apache.commons.lang3.Validate.notEmpty(Validate.java:398)
	at ru.<init>(SourceFile:29)
	at wu.a(SourceFile:94)
	at abo.D(SourceFile:594)
	at rg.h(SourceFile:1195)
	at xk.h(SourceFile:240)
	at ml.i(SourceFile:207)
	at mw.a(SourceFile:209)
	at iq.a(SourceFile:137)
	at is.a(SourceFile:20)
	at ef.a(SourceFile:143)
	at mr.c(SourceFile:134)
	at net.minecraft.server.MinecraftServer.u(SourceFile:529)
	at net.minecraft.server.MinecraftServer.t(SourceFile:441)
	at bsi.t(SourceFile:117)
	at net.minecraft.server.MinecraftServer.run(SourceFile:358)
	at kx.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 ru.<init>(SourceFile:29)
	at wu.a(SourceFile:94)
	at abo.D(SourceFile:594)
	at rg.h(SourceFile:1195)
	at xk.h(SourceFile:240)

-- Player being ticked --
Details:
	Entity Type: null (ml)
	Entity ID: 26
	Entity Name: Broken_Ghost
	Entity's Exact location: -711.12, 56.00, 140.30
	Entity's Block location: World: (-712,56,140), Chunk: (at 8,3,12 in -45,8; contains blocks -720,0,128 to -705,255,143), Region: (-2,0; contains chunks -64,0 to -33,31, blocks -1024,0,0 to -513,255,511)
	Entity's Momentum: 0.00, -0.08, 0.00
Stacktrace:
	at ml.i(SourceFile:207)
	at mw.a(SourceFile:209)
	at iq.a(SourceFile:137)
	at is.a(SourceFile:20)
	at ef.a(SourceFile:143)

-- Ticking connection --
Details:
	Connection: ef@328c3770
Stacktrace:
	at mr.c(SourceFile:134)
	at net.minecraft.server.MinecraftServer.u(SourceFile:529)
	at net.minecraft.server.MinecraftServer.t(SourceFile:441)
	at bsi.t(SourceFile:117)
	at net.minecraft.server.MinecraftServer.run(SourceFile:358)
	at kx.run(SourceFile:617)

-- System Details --
Details:
	Minecraft Version: 1.7.1
	Operating System: Mac OS X (x86_64) version 10.8.5
	Java Version: 1.6.0_51, Apple Inc.
	Java VM Version: Java HotSpot(TM) 64-Bit Server VM (mixed mode), Apple Inc.
	Memory: 65737392 bytes (62 MB) / 147111936 bytes (140 MB) up to 1065025536 bytes (1015 MB)
	JVM Flags: 1 total; -Xmx1G
	AABB Pool Size: 258 (14448 bytes; 0 MB) allocated, 258 (14448 bytes; 0 MB) used
	IntCache: cache: 0, tcache: 0, allocated: 0, tallocated: 0
	Profiler Position: N/A (disabled)
	Vec3 Pool Size: 15 (840 bytes; 0 MB) allocated, 15 (840 bytes; 0 MB) used
	Player Count: 1 / 8; [ml['Broken_Ghost'/26, l='Vampire', x=-711.12, y=56.00, z=140.30]]
	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-449442/20924167/