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-191762/

Crash:

java.lang.IllegalArgumentException: Modifier name cannot be empty
	at org.apache.commons.lang3.Validate.notEmpty(Validate.java:398)
	at ot.<init>(SourceFile:31)
	at tp.a(SourceFile:94)
	at ye.D(SourceFile:580)
	at ye.a(SourceFile:471)
	at awy.a(SourceFile:188)
	at awy.a(SourceFile:168)

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

---- Minecraft Crash Report ----
// There are four lights!

Time: 19-09-13 20:22
Description: Rendering screen

java.lang.IllegalArgumentException: Modifier name cannot be empty
	at org.apache.commons.lang3.Validate.notEmpty(Validate.java:398)
	at ot.<init>(SourceFile:31)
	at tp.a(SourceFile:94)
	at ye.D(SourceFile:580)
	at ye.a(SourceFile:471)
	at awy.a(SourceFile:188)
	at awy.a(SourceFile:168)
	at bfe.b(SourceFile:718)
	at atv.S(SourceFile:686)
	at atv.d(SourceFile:619)
	at net.minecraft.client.main.Main.main(SourceFile:101)


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 ot.<init>(SourceFile:31)
	at tp.a(SourceFile:94)
	at ye.D(SourceFile:580)
	at ye.a(SourceFile:471)
	at awy.a(SourceFile:188)
	at awy.a(SourceFile:168)

-- Screen render details --
Details:
	Screen name: axj
	Mouse location: Scaled: (173, 71). Absolute: (695, 734)
	Screen size: Scaled: (480, 255). Absolute: (1920, 1018). Scale factor of 4

-- Affected level --
Details:
	Level name: MpServer
	All players: 1 total; [bdi['holle9999'/50, l='MpServer', x=460,29, y=44,50, z=-600,83]]
	Chunk stats: MultiplayerChunkCache: 441
	Level seed: 0
	Level generator: ID 01 - flat, ver 0. Features enabled: false
	Level generator options: 
	Level spawn location: World: (635,4,-610), Chunk: (at 11,0,14 in 39,-39; contains blocks 624,0,-624 to 639,255,-609), Region: (1,-2; contains chunks 32,-64 to 63,-33, blocks 512,0,-1024 to 1023,255,-513)
	Level time: 7728764 game time, 116219 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: 42 total; [su['entity.MinecartChest.name'/2, l='MpServer', x=471,50, y=48,50, z=-624,50], sy['entity.MinecartRideable.name'/3, l='MpServer', x=480,50, y=42,50, z=-615,53], od['entity.ItemFrame.name'/4, l='MpServer', x=522,06, y=58,50, z=-663,50], od['entity.ItemFrame.name'/5, l='MpServer', x=515,06, y=57,50, z=-629,50], od['entity.ItemFrame.name'/6, l='MpServer', x=515,06, y=57,50, z=-630,50], od['entity.ItemFrame.name'/7, l='MpServer', x=515,06, y=57,50, z=-631,50], od['entity.ItemFrame.name'/8, l='MpServer', x=515,06, y=56,50, z=-629,50], od['entity.ItemFrame.name'/9, l='MpServer', x=515,06, y=56,50, z=-630,50], od['entity.ItemFrame.name'/10, l='MpServer', x=515,06, y=56,50, z=-631,50], rq['Chicken'/11, l='MpServer', x=522,84, y=45,00, z=-552,34], rq['Chicken'/12, l='MpServer', x=522,16, y=45,00, z=-552,84], bdi['holle9999'/50, l='MpServer', x=460,29, y=44,50, z=-600,83], rq['Chicken'/13, l='MpServer', x=523,84, y=45,00, z=-552,34], rz['Sheep'/14, l='MpServer', x=523,53, y=45,50, z=-551,50], rq['Chicken'/15, l='MpServer', x=526,47, y=45,00, z=-552,28], od['entity.ItemFrame.name'/17, l='MpServer', x=533,50, y=57,50, z=-565,06], od['entity.ItemFrame.name'/16, l='MpServer', x=534,50, y=57,50, z=-565,06], od['entity.ItemFrame.name'/19, l='MpServer', x=535,50, y=57,50, z=-571,06], od['entity.ItemFrame.name'/18, l='MpServer', x=532,50, y=57,50, z=-565,06], ol['Painting'/21, l='MpServer', x=558,94, y=58,00, z=-568,00], od['entity.ItemFrame.name'/23, l='MpServer', x=579,06, y=60,50, z=-629,50], ol['Painting'/22, l='MpServer', x=582,94, y=60,00, z=-630,00], od['entity.ItemFrame.name'/25, l='MpServer', x=579,06, y=59,50, z=-629,50], od['entity.ItemFrame.name'/24, l='MpServer', x=579,06, y=60,50, z=-630,50], od['entity.ItemFrame.name'/26, l='MpServer', x=579,06, y=59,50, z=-630,50], od['entity.ItemFrame.name'/29, l='MpServer', x=602,50, y=59,50, z=-643,94], od['entity.ItemFrame.name'/28, l='MpServer', x=600,50, y=59,50, z=-643,94], od['entity.ItemFrame.name'/31, l='MpServer', x=595,50, y=59,50, z=-643,94], od['entity.ItemFrame.name'/30, l='MpServer', x=601,50, y=59,50, z=-643,94], od['entity.ItemFrame.name'/34, l='MpServer', x=603,94, y=58,50, z=-612,50], od['entity.ItemFrame.name'/35, l='MpServer', x=603,94, y=58,50, z=-614,50], od['entity.ItemFrame.name'/32, l='MpServer', x=594,50, y=59,50, z=-643,94], od['entity.ItemFrame.name'/33, l='MpServer', x=593,50, y=59,50, z=-643,94], od['entity.ItemFrame.name'/39, l='MpServer', x=603,94, y=58,50, z=-602,50], od['entity.ItemFrame.name'/37, l='MpServer', x=603,94, y=58,50, z=-613,50], ol['Painting'/21, l='MpServer', x=558,94, y=58,00, z=-568,00], od['entity.ItemFrame.name'/42, l='MpServer', x=603,94, y=58,50, z=-602,50], od['entity.ItemFrame.name'/43, l='MpServer', x=603,94, y=58,50, z=-601,50], od['entity.ItemFrame.name'/40, l='MpServer', x=603,94, y=58,50, z=-601,50], od['entity.ItemFrame.name'/41, l='MpServer', x=603,94, y=58,50, z=-600,50], oe['entity.LeashKnot.name'/49, l='MpServer', x=558,50, y=56,50, z=-586,50], ol['Painting'/22, l='MpServer', x=582,94, y=60,00, z=-630,00]]
	Retry entities: 0 total; []
	Server brand: vanilla
	Server type: Integrated singleplayer server
Stacktrace:
	at bdd.a(SourceFile:284)
	at atv.b(SourceFile:1761)
	at atv.d(SourceFile:628)
	at net.minecraft.client.main.Main.main(SourceFile:101)

-- System Details --
Details:
	Minecraft Version: 1.6.4
	Operating System: Windows 7 (amd64) version 6.1
	Java Version: 1.7.0_07, Oracle Corporation
	Java VM Version: Java HotSpot(TM) 64-Bit Server VM (mixed mode), Oracle Corporation
	Memory: 177697320 bytes (169 MB) / 426049536 bytes (406 MB) up to 954466304 bytes (910 MB)
	JVM Flags: 2 total; -XX:HeapDumpPath=MojangTricksIntelDriversForPerformance_javaw.exe_minecraft.exe.heapdump -Xmx1G
	AABB Pool Size: 21751 (1218056 bytes; 1 MB) allocated, 5 (280 bytes; 0 MB) used
	Suspicious classes: No suspicious classes found.
	IntCache: cache: 0, tcache: 0, allocated: 0, tallocated: 0
	Launched Version: 1.6.4
	LWJGL: 2.9.0
	OpenGL: AMD Radeon HD 6900M Series   GL version 4.1.10765 Compatibility Profile Context, ATI Technologies Inc.
	Is Modded: Probably not. Jar signature remains and client brand is untouched.
	Type: Client (map_client.txt)
	Resource Pack: Default
	Current Language: English (US)
	Profiler Position: N/A (disabled)
	Vec3 Pool Size: 238 (13328 bytes; 0 MB) allocated, 33 (1848 bytes; 0 MB) used

You can see this full report at http://hopper.minecraft.net/crashes/minecraft/MCX-191762/12418148/