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-465470/

Crash:

java.lang.IllegalArgumentException: Modifier name cannot be empty
	at org.apache.commons.lang3.Validate.notEmpty(Validate.java:398)
	at rv.<init>(SourceFile:29)
	at wv.a(SourceFile:94)
	at abp.D(SourceFile:594)
	at abp.a(SourceFile:482)
	at bcd.a(SourceFile:76)
	at bdd.a(SourceFile:166)

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

---- Minecraft Crash Report ----
// Oh - I know what I did wrong!

Time: 25.10.13 20:50
Description: Rendering screen

java.lang.IllegalArgumentException: Modifier name cannot be empty
	at org.apache.commons.lang3.Validate.notEmpty(Validate.java:398)
	at rv.<init>(SourceFile:29)
	at wv.a(SourceFile:94)
	at abp.D(SourceFile:594)
	at abp.a(SourceFile:482)
	at bcd.a(SourceFile:76)
	at bdd.a(SourceFile:166)
	at bll.b(SourceFile:851)
	at azd.ad(SourceFile:780)
	at azd.e(SourceFile:704)
	at net.minecraft.client.main.Main.main(SourceFile:103)


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 rv.<init>(SourceFile:29)
	at wv.a(SourceFile:94)
	at abp.D(SourceFile:594)
	at abp.a(SourceFile:482)
	at bcd.a(SourceFile:76)
	at bdd.a(SourceFile:166)

-- Screen render details --
Details:
	Screen name: bdo
	Mouse location: Scaled: (149, 66). Absolute: (299, 346)
	Screen size: Scaled: (427, 240). Absolute: (854, 480). Scale factor of 2

-- Affected level --
Details:
	Level name: MpServer
	All players: 1 total; [bje['damianpila'/14419, l='MpServer', x=-6,57, y=5,62, z=38,00]]
	Chunk stats: MultiplayerChunkCache: 225, 225
	Level seed: 0
	Level generator: ID 01 - flat, ver 0. Features enabled: false
	Level generator options: 
	Level spawn location: World: (-7,4,41), Chunk: (at 9,0,9 in -1,2; contains blocks -16,0,32 to -1,255,47), Region: (-1,0; contains chunks -32,0 to -1,31, blocks -512,0,0 to -1,255,511)
	Level time: 1441 game time, 1441 day time
	Level dimension: 0
	Level storage version: 0x00000 - Unknown?
	Level weather: Rain time: 0 (now: false), thunder time: 0 (now: false)
	Level game mode: Game mode: creative (ID 1). Hardcore: false. Cheats: false
	Forced entities: 4 total; [wy['Szlam'/15887, l='MpServer', x=-31,42, y=4,00, z=23,20], bje['damianpila'/14419, l='MpServer', x=-6,57, y=5,62, z=38,00], wy['Szlam'/16144, l='MpServer', x=6,39, y=5,06, z=15,33], wy['Szlam'/14408, l='MpServer', x=-32,32, y=4,95, z=-8,80]]
	Retry entities: 0 total; []
	Server brand: vanilla
	Server type: Integrated singleplayer server
Stacktrace:
	at biz.a(SourceFile:284)
	at azd.b(SourceFile:1951)
	at azd.e(SourceFile:713)
	at net.minecraft.client.main.Main.main(SourceFile:103)

-- System Details --
Details:
	Minecraft Version: 1.7.2
	Operating System: Windows 7 (x86) version 6.1
	Java Version: 1.7.0_40, Oracle Corporation
	Java VM Version: Java HotSpot(TM) Client VM (mixed mode, sharing), Oracle Corporation
	Memory: 219692824 bytes (209 MB) / 383676416 bytes (365 MB) up to 518979584 bytes (494 MB)
	JVM Flags: 2 total; -XX:HeapDumpPath=MojangTricksIntelDriversForPerformance_javaw.exe_minecraft.exe.heapdump -Xmx512M
	AABB Pool Size: 7843 (439208 bytes; 0 MB) allocated, 5 (280 bytes; 0 MB) used
	IntCache: cache: 0, tcache: 0, allocated: 13, tallocated: 95
	Launched Version: 1.7.2
	LWJGL: 2.9.0
	OpenGL: AMD M880G with ATI Mobility Radeon HD 4200  GL version 2.1.8796, ATI Technologies Inc.
	Is Modded: Probably not. Jar signature remains and client brand is untouched.
	Type: Client (map_client.txt)
	Resource Packs: []
	Current Language: Polski (Polska)
	Profiler Position: N/A (disabled)
	Vec3 Pool Size: 252 (14112 bytes; 0 MB) allocated, 35 (1960 bytes; 0 MB) used
	Anisotropic Filtering: Off (1)

You can see this full report at http://hopper.minecraft.net/crashes/minecraft/MCX-465470/21456334/