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-74640/

Crash:

java.lang.IllegalArgumentException: n must be positive
	at java.util.Random.nextInt(Unknown Source)
	at adu.a(SourceFile:121)
	at adu.a(SourceFile:26)
	at ado.a(SourceFile:350)
	at aej.a(SourceFile:74)
	at afw.a(SourceFile:156)
	at kc.a(SourceFile:156)
	at aey.a(SourceFile:774)
	at kc.c(SourceFile:93)
	at kb.<init>(SourceFile:28)
	at ka.a(SourceFile:209)
	at ka.a(SourceFile:246)
	at hx.a(SourceFile:151)
	at hx.c(SourceFile:199)
	at hx.a(SourceFile:95)
	at bnj.b(SourceFile:73)
	at net.minecraft.server.MinecraftServer.t(SourceFile:481)
	at net.minecraft.server.MinecraftServer.s(SourceFile:398)
	at bng.s(SourceFile:124)
	at net.minecraft.server.MinecraftServer.run(SourceFile:332)
	at hs.run(SourceFile:575)

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

---- Minecraft Crash Report ----
// Surprise! Haha. Well, this is awkward.

Time: 05/09/13 19.04
Description: Exception in server tick loop

java.lang.IllegalArgumentException: n must be positive
	at java.util.Random.nextInt(Unknown Source)
	at adu.a(SourceFile:121)
	at adu.a(SourceFile:26)
	at ado.a(SourceFile:350)
	at aej.a(SourceFile:74)
	at afw.a(SourceFile:156)
	at kc.a(SourceFile:156)
	at aey.a(SourceFile:774)
	at kc.c(SourceFile:93)
	at kb.<init>(SourceFile:28)
	at ka.a(SourceFile:209)
	at ka.a(SourceFile:246)
	at hx.a(SourceFile:151)
	at hx.c(SourceFile:199)
	at hx.a(SourceFile:95)
	at bnj.b(SourceFile:73)
	at net.minecraft.server.MinecraftServer.t(SourceFile:481)
	at net.minecraft.server.MinecraftServer.s(SourceFile:398)
	at bng.s(SourceFile:124)
	at net.minecraft.server.MinecraftServer.run(SourceFile:332)
	at hs.run(SourceFile:575)


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

-- System Details --
Details:
	Minecraft Version: 13w36a
	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: 232321168 bytes (221 MB) / 612302848 bytes (583 MB) up to 1908932608 bytes (1820 MB)
	JVM Flags: 2 total; -XX:HeapDumpPath=MojangTricksIntelDriversForPerformance_javaw.exe_minecraft.exe.heapdump -Xmx2G
	AABB Pool Size: 2561 (143416 bytes; 0 MB) allocated, 2561 (143416 bytes; 0 MB) used
	Suspicious classes: [com.ibm.icu.text.ArabicShapingException], [gnu.trove.TIntCollection], [gnu.trove.impl.HashFunctions, PrimeFinder], [gnu.trove.impl.hash.THash, TPrimitiveHash, TIntIntHash], [gnu.trove.iterator.TIterator, TAdvancingIterator, TIntIntIterator], [gnu.trove.map.TIntIntMap], [gnu.trove.map.hash.TIntIntHashMap], [gnu.trove.procedure.TIntIntProcedure], [gnu.trove.set.TIntSet]
	IntCache: cache: 0, tcache: 0, allocated: 0, tallocated: 0
	Profiler Position: N/A (disabled)
	Vec3 Pool Size: 799 (44744 bytes; 0 MB) allocated, 799 (44744 bytes; 0 MB) used
	Player Count: 1 / 8; [kg['flb8'/2768, l='Mondo piatto per server', x=111,46, y=92,11, z=247,93]]
	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-74640/8129224/