Hopper: java.lang.ArrayIndexOutOfBoundsException: -1

java.lang.ArrayIndexOutOfBoundsException: -1
	at acv.a(SourceFile:135)
	at aet.a(SourceFile:72)
	at aet.d(SourceFile:213)

---- Minecraft Crash Report ----
// Why is it breaking :(

Time: 9/19/13 7:07 PM
Description: Exception generating new chunk

java.lang.ArrayIndexOutOfBoundsException: -1
	at acv.a(SourceFile:135)
	at aet.a(SourceFile:72)
	at aet.d(SourceFile:213)
	at jr.c(SourceFile:84)
	at jq.<init>(SourceFile:29)
	at jp.a(SourceFile:208)
	at jp.a(SourceFile:240)
	at hn.a(SourceFile:141)
	at hn.c(SourceFile:188)
	at hn.a(SourceFile:85)
	at blc.b(SourceFile:73)
	at net.minecraft.server.MinecraftServer.t(SourceFile:489)
	at net.minecraft.server.MinecraftServer.s(SourceFile:406)
	at bkz.s(SourceFile:124)
	at net.minecraft.server.MinecraftServer.run(SourceFile:340)
	at hi.run(SourceFile:583)


A detailed walkthrough of the error, its code path and all known details is as follows:
---------------------------------------------------------------------------------------

-- Head --
Stacktrace:
	at acv.a(SourceFile:135)
	at aet.a(SourceFile:72)
	at aet.d(SourceFile:213)

-- Chunk to be generated --
Details:
	Location: -165,-18
	Position hash: -73014444197
	Generator: RandomLevelSource
Stacktrace:
	at jr.c(SourceFile:84)
	at jq.<init>(SourceFile:29)
	at jp.a(SourceFile:208)
	at jp.a(SourceFile:240)
	at hn.a(SourceFile:141)
	at hn.c(SourceFile:188)
	at hn.a(SourceFile:85)
	at blc.b(SourceFile:73)
	at net.minecraft.server.MinecraftServer.t(SourceFile:489)
	at net.minecraft.server.MinecraftServer.s(SourceFile:406)
	at bkz.s(SourceFile:124)
	at net.minecraft.server.MinecraftServer.run(SourceFile:340)
	at hi.run(SourceFile:583)

-- System Details --
Details:
	Minecraft Version: 1.6.4
	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: 71171200 bytes (67 MB) / 151990272 bytes (144 MB) up to 1065025536 bytes (1015 MB)
	JVM Flags: 1 total; -Xmx1G
	AABB Pool Size: 2150 (120400 bytes; 0 MB) allocated, 2150 (120400 bytes; 0 MB) used
	Suspicious classes: No suspicious classes found.
	IntCache: cache: 0, tcache: 0, allocated: 4, tallocated: 78
	Profiler Position: N/A (disabled)
	Vec3 Pool Size: 238 (13328 bytes; 0 MB) allocated, 238 (13328 bytes; 0 MB) used
	Player Count: 1 / 8; [jv['Maximus_Coolicus'/203, l='New Survival World', x=-2470.72, y=65.00, z=-365.26]]
	Type: Integrated Server (map_client.txt)
	Is Modded: Probably not. Jar signature remains and both client + server brands are untouched.