I tried to make a customized world, and.... crashed.

↓this is the crash report
(오후 means afternoon)

---- Minecraft Crash Report ----
// Hey, that tickles! Hehehe!

Time: 14. 4. 25 오후 7:22
Description: Exception in server tick loop

java.lang.IllegalArgumentException: n must be positive
at java.util.Random.nextInt(Unknown Source)
at ayy.a(SourceFile:442)
at od.a(SourceFile:175)
at axr.a(SourceFile:859)
at od.c(SourceFile:104)
at net.minecraft.server.MinecraftServer.i(SourceFile:269)
at cim.a(SourceFile:94)
at cim.g(SourceFile:110)
at net.minecraft.server.MinecraftServer.run(SourceFile:367)
at mu.run(SourceFile:667)

A detailed walkthrough of the error, its code path and all known details is as follows:
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– System Details –
Details:
Minecraft Version: 14w17a
Operating System: Windows 8 (amd64) version 6.2
Java Version: 1.7.0_51, Oracle Corporation
Java VM Version: Java HotSpot(TM) 64-Bit Server VM (mixed mode), Oracle Corporation
Memory: 552728912 bytes (527 MB) / 660078592 bytes (629 MB) up to 3817865216 bytes (3641 MB)
JVM Flags: 2 total; -XX:HeapDumpPath=MojangTricksIntelDriversForPerformance_javaw.exe_minecraft.exe.heapdump -Xmx4G
IntCache: cache: 0, tcache: 0, allocated: 13, tallocated: 93
Profiler Position: N/A (disabled)
Player Count: 0 / 8; []
Type: Integrated Server (map_client.txt)
Is Modded: Probably not. Jar signature remains and both client + server brands are untouched.