Hopper: java.lang.ArrayIndexOutOfBoundsException: -1

This is an automatically generated report based from the following crash: http://hopper.minecraft.net/crashes/minecraft/MCX-191150/

Crash:

java.lang.ArrayIndexOutOfBoundsException: -1
	at acv.a(SourceFile:81)
	at act.<init>(SourceFile:29)
	at acs.a(SourceFile:59)
	at acs.e(SourceFile:98)
	at acv.a(SourceFile:161)
	at acv.b(SourceFile:151)
	at aet.d(SourceFile:214)

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

---- Minecraft Crash Report ----
// I blame Dinnerbone.

Time: 9/19/13 10:53 PM
Description: Exception generating new chunk

java.lang.ArrayIndexOutOfBoundsException: -1
	at acv.a(SourceFile:81)
	at act.<init>(SourceFile:29)
	at acs.a(SourceFile:59)
	at acs.e(SourceFile:98)
	at acv.a(SourceFile:161)
	at acv.b(SourceFile:151)
	at aet.d(SourceFile:214)
	at jr.c(SourceFile:84)
	at jr.d(SourceFile:116)
	at abw.e(SourceFile:289)
	at abw.a(SourceFile:213)
	at acj.b(SourceFile:84)
	at acj.a(SourceFile:49)
	at hn.a(SourceFile:422)
	at hn.a(SourceFile:352)
	at jv.b(SourceFile:296)
	at nn.y(SourceFile:315)
	at of.y(SourceFile:163)
	at nn.l_(SourceFile:278)
	at of.l_(SourceFile:1149)
	at uf.l_(SourceFile:203)
	at jv.h(SourceFile:185)
	at ka.a(SourceFile:190)
	at eu.a(SourceFile:136)
	at cn.b(SourceFile:64)
	at ka.e(SourceFile:60)
	at kd.b(SourceFile:37)
	at blc.b(SourceFile:84)
	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:81)
	at act.<init>(SourceFile:29)
	at acs.a(SourceFile:59)
	at acs.e(SourceFile:98)
	at acv.a(SourceFile:161)
	at acv.b(SourceFile:151)
	at aet.d(SourceFile:214)

-- Chunk to be generated --
Details:
	Location: 280,82
	Position hash: 352187318552
	Generator: RandomLevelSource
Stacktrace:
	at jr.c(SourceFile:84)
	at jr.d(SourceFile:116)
	at abw.e(SourceFile:289)

-- Requested block coordinates --
Details:
	Found chunk: true
	Location: World: (4482,255,1312), Chunk: (at 2,15,0 in 280,82; contains blocks 4480,0,1312 to 4495,255,1327), Region: (8,2; contains chunks 256,64 to 287,95, blocks 4096,0,1024 to 4607,255,1535)
Stacktrace:
	at abw.a(SourceFile:213)
	at acj.b(SourceFile:84)
	at acj.a(SourceFile:49)
	at hn.a(SourceFile:422)
	at hn.a(SourceFile:352)
	at jv.b(SourceFile:296)
	at nn.y(SourceFile:315)
	at of.y(SourceFile:163)
	at nn.l_(SourceFile:278)
	at of.l_(SourceFile:1149)
	at uf.l_(SourceFile:203)

-- Player being ticked --
Details:
	Entity Type: null (jv)
	Entity ID: 221
	Entity Name: Ams71293
	Entity's Exact location: 4610.00, 93.00, 1202.00
	Entity's Block location: World: (4610,93,1202), Chunk: (at 2,5,2 in 288,75; contains blocks 4608,0,1200 to 4623,255,1215), Region: (9,2; contains chunks 288,64 to 319,95, blocks 4608,0,1024 to 5119,255,1535)
	Entity's Momentum: 0.22, -0.23, -0.01
Stacktrace:
	at jv.h(SourceFile:185)
	at ka.a(SourceFile:190)
	at eu.a(SourceFile:136)
	at cn.b(SourceFile:64)
	at ka.e(SourceFile:60)

-- Ticking connection --
Details:
	Connection: ka@53ac9aea
Stacktrace:
	at kd.b(SourceFile:37)
	at blc.b(SourceFile:84)
	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: Windows 7 (amd64) version 6.1
	Java Version: 1.6.0_24, Sun Microsystems Inc.
	Java VM Version: Java HotSpot(TM) 64-Bit Server VM (mixed mode), Sun Microsystems Inc.
	Memory: 408812208 bytes (389 MB) / 674889728 bytes (643 MB) up to 954466304 bytes (910 MB)
	JVM Flags: 2 total; -XX:HeapDumpPath=MojangTricksIntelDriversForPerformance_javaw.exe_minecraft.exe.heapdump -Xmx1G
	AABB Pool Size: 1712 (95872 bytes; 0 MB) allocated, 1563 (87528 bytes; 0 MB) used
	Suspicious classes: No suspicious classes found.
	IntCache: cache: 1, tcache: 23, allocated: 3, tallocated: 63
	Profiler Position: N/A (disabled)
	Vec3 Pool Size: 0 (0 bytes; 0 MB) allocated, 0 (0 bytes; 0 MB) used
	Player Count: 1 / 8; [jv['Ams71293'/221, l='Allen and Stephy', x=4610.00, y=93.00, z=1202.00]]
	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-191150/12512040/