Hopper: java.lang.IllegalArgumentException: n must be positive

This is an automatically generated report based from the following crash: http://hopper.minecraft.net/crashes/minecraft/MCX-470459/

Crash:

java.lang.IllegalArgumentException: n must be positive
	at java.util.Random.nextInt(Unknown Source)
	at agm.a(SourceFile:130)
	at agm.a(SourceFile:27)
	at agg.a(SourceFile:362)
	at ago.a(SourceFile:29)
	at apg.a(SourceFile:162)
	at mi.a(SourceFile:160)
	at aoj.a(SourceFile:778)
	at mi.c(SourceFile:95)
	at mi.d(SourceFile:108)
	at afn.e(SourceFile:311)

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

---- Minecraft Crash Report ----
// Daisy, daisy...

Time: 25/10/13 5:08 PM
Description: Exception getting block type in world

java.lang.IllegalArgumentException: n must be positive
	at java.util.Random.nextInt(Unknown Source)
	at agm.a(SourceFile:130)
	at agm.a(SourceFile:27)
	at agg.a(SourceFile:362)
	at ago.a(SourceFile:29)
	at apg.a(SourceFile:162)
	at mi.a(SourceFile:160)
	at aoj.a(SourceFile:778)
	at mi.c(SourceFile:95)
	at mi.d(SourceFile:108)
	at afn.e(SourceFile:311)
	at afn.a(SourceFile:249)
	at afn.e(SourceFile:477)
	at afn.d(SourceFile:463)
	at afn.c(SourceFile:428)
	at afn.d(SourceFile:337)
	at afn.f(SourceFile:390)
	at ajj.m(SourceFile:46)
	at ajj.a(SourceFile:35)
	at mj.a(SourceFile:405)
	at mj.b(SourceFile:134)
	at net.minecraft.server.MinecraftServer.u(SourceFile:503)
	at net.minecraft.server.MinecraftServer.t(SourceFile:441)
	at bsk.t(SourceFile:117)
	at net.minecraft.server.MinecraftServer.run(SourceFile:358)
	at ky.run(SourceFile:617)


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

-- Head --
Stacktrace:
	at java.util.Random.nextInt(Unknown Source)
	at agm.a(SourceFile:130)
	at agm.a(SourceFile:27)
	at agg.a(SourceFile:362)
	at ago.a(SourceFile:29)
	at apg.a(SourceFile:162)
	at mi.a(SourceFile:160)
	at aoj.a(SourceFile:778)
	at mi.c(SourceFile:95)
	at mi.d(SourceFile:108)
	at afn.e(SourceFile:311)

-- Requested block coordinates --
Details:
	Found chunk: true
	Location: World: (783,0,-656), Chunk: (at 15,0,0 in 48,-41; contains blocks 768,0,-656 to 783,255,-641), Region: (1,-2; contains chunks 32,-64 to 63,-33, blocks 512,0,-1024 to 1023,255,-513)
Stacktrace:
	at afn.a(SourceFile:249)
	at afn.e(SourceFile:477)
	at afn.d(SourceFile:463)
	at afn.c(SourceFile:428)
	at afn.d(SourceFile:337)
	at afn.f(SourceFile:390)
	at ajj.m(SourceFile:46)
	at ajj.a(SourceFile:35)

-- Block being ticked --
Details:
	Block type: ID #12 (tile.sand // alt)
	Block data value: 0 / 0x0 / 0b0000
	Block location: World: (783,0,-657), Chunk: (at 15,0,15 in 48,-42; contains blocks 768,0,-672 to 783,255,-657), Region: (1,-2; contains chunks 32,-64 to 63,-33, blocks 512,0,-1024 to 1023,255,-513)
Stacktrace:
	at mj.a(SourceFile:405)
	at mj.b(SourceFile:134)

-- Affected level --
Details:
	Level name: Copy of New World
	All players: 1 total; [mm['cool_master786'/6008, l='Copy of New World', x=979.27, y=2.17, z=-688.18]]
	Chunk stats: ServerChunkCache: 1213 Drop: 0
	Level seed: -5766278616093217242
	Level generator: ID 01 - flat, ver 0. Features enabled: true
	Level generator options: 2;12;2;stronghold,biome_1,village,decoration,dungeon,mineshaft
	Level spawn location: World: (983,4,-685), Chunk: (at 7,0,3 in 61,-43; contains blocks 976,0,-688 to 991,255,-673), Region: (1,-2; contains chunks 32,-64 to 63,-33, blocks 512,0,-1024 to 1023,255,-513)
	Level time: 230 game time, 230 day time
	Level dimension: 0
	Level storage version: 0x04ABD - Anvil
	Level weather: Rain time: 170570 (now: false), thunder time: 17872 (now: false)
	Level game mode: Game mode: creative (ID 1). Hardcore: false. Cheats: true
Stacktrace:
	at net.minecraft.server.MinecraftServer.u(SourceFile:503)
	at net.minecraft.server.MinecraftServer.t(SourceFile:441)
	at bsk.t(SourceFile:117)
	at net.minecraft.server.MinecraftServer.run(SourceFile:358)
	at ky.run(SourceFile:617)

-- System Details --
Details:
	Minecraft Version: 1.7.2
	Operating System: Windows 8 (amd64) version 6.2
	Java Version: 1.7.0_25, Oracle Corporation
	Java VM Version: Java HotSpot(TM) 64-Bit Server VM (mixed mode), Oracle Corporation
	Memory: 197971552 bytes (188 MB) / 394854400 bytes (376 MB) up to 954466304 bytes (910 MB)
	JVM Flags: 2 total; -XX:HeapDumpPath=MojangTricksIntelDriversForPerformance_javaw.exe_minecraft.exe.heapdump -Xmx1G
	AABB Pool Size: 86342 (4835152 bytes; 4 MB) allocated, 0 (0 bytes; 0 MB) used
	IntCache: cache: 0, tcache: 0, allocated: 13, tallocated: 95
	Profiler Position: N/A (disabled)
	Vec3 Pool Size: 517 (28952 bytes; 0 MB) allocated, 0 (0 bytes; 0 MB) used
	Player Count: 1 / 8; [mm['cool_master786'/6008, l='Copy of New World', x=979.27, y=2.17, z=-688.18]]
	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-470459/21588205/