Hopper: java.lang.ArrayIndexOutOfBoundsException: -1

This is an automatically generated report based from the following crash: http://hopper.minecraft.net/crashes/minecraft/MCX-190776/

Crash:

java.lang.ArrayIndexOutOfBoundsException: -1
	at acv.a(SourceFile:81)
	at act.<init>(SourceFile:29)
	at acs.a(SourceFile:59)
	at acs.b(SourceFile:68)
	at acv.a(SourceFile:61)
	at adr.a(SourceFile:865)
	at abw.a(SourceFile:92)
	at abw.a(SourceFile:1030)
	at bfe.i(SourceFile:1184)
	at bfe.a(SourceFile:784)

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

---- Minecraft Crash Report ----
// Don't do that.

Time: 9/19/13 3:16 PM
Description: Unexpected error

java.lang.ArrayIndexOutOfBoundsException: -1
	at acv.a(SourceFile:81)
	at act.<init>(SourceFile:29)
	at acs.a(SourceFile:59)
	at acs.b(SourceFile:68)
	at acv.a(SourceFile:61)
	at adr.a(SourceFile:865)
	at abw.a(SourceFile:92)
	at abw.a(SourceFile:1030)
	at bfe.i(SourceFile:1184)
	at bfe.a(SourceFile:784)
	at bfe.b(SourceFile:693)
	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 acv.a(SourceFile:81)
	at act.<init>(SourceFile:29)
	at acs.a(SourceFile:59)
	at acs.b(SourceFile:68)
	at acv.a(SourceFile:61)
	at adr.a(SourceFile:865)
	at abw.a(SourceFile:92)
	at abw.a(SourceFile:1030)
	at bfe.i(SourceFile:1184)
	at bfe.a(SourceFile:784)

-- Affected level --
Details:
	Level name: MpServer
	All players: 1 total; [bdi['1337Cupcake'/215, l='MpServer', x=8.50, y=66.62, z=8.50]]
	Chunk stats: MultiplayerChunkCache: 0
	Level seed: 0
	Level generator: ID 00 - default, ver 1. Features enabled: false
	Level generator options: 
	Level spawn location: World: (4,64,256), Chunk: (at 4,4,0 in 0,16; contains blocks 0,0,256 to 15,255,271), Region: (0,0; contains chunks 0,0 to 31,31, blocks 0,0,0 to 511,255,511)
	Level time: 12523 game time, 12523 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: survival (ID 0). Hardcore: false. Cheats: false
	Forced entities: 1 total; [bdi['1337Cupcake'/215, l='MpServer', x=8.50, y=66.62, z=8.50]]
	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:633)
	at net.minecraft.client.main.Main.main(SourceFile:101)

-- System Details --
Details:
	Minecraft Version: 1.6.4
	Operating System: Mac OS X (x86_64) version 10.8.4
	Java Version: 1.6.0_51, Apple Inc.
	Java VM Version: Java HotSpot(TM) 64-Bit Server VM (mixed mode), Apple Inc.
	Memory: 71923280 bytes (68 MB) / 158113792 bytes (150 MB) up to 1065025536 bytes (1015 MB)
	JVM Flags: 1 total; -Xmx1G
	AABB Pool Size: 4627 (259112 bytes; 0 MB) allocated, 4627 (259112 bytes; 0 MB) used
	Suspicious classes: No suspicious classes found.
	IntCache: cache: 1, tcache: 3, allocated: 1, tallocated: 63
	Launched Version: 1.6.4
	LWJGL: 2.9.0
	OpenGL: NVIDIA GeForce GT 640M OpenGL Engine GL version 2.1 NVIDIA-8.12.47 310.40.00.05f01, NVIDIA Corporation
	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: 13 (728 bytes; 0 MB) allocated, 13 (728 bytes; 0 MB) used

You can see this full report at http://hopper.minecraft.net/crashes/minecraft/MCX-190776/12416743/