Problem/Bug Server Crashes when someone join

I have a bukkit server, i can connect to my server, but when my friend join, the server crashes...i don't know what is the problem but here is the crash report

Code:

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

Time: 12/24/14 9:14 AM
Description: Exception in server tick loop

java.lang.IllegalArgumentException: bound must be positive
    at java.util.Random.nextInt(Unknown Source)
    at net.minecraft.server.v1_8_R1.BiomeDecorator.a(BiomeDecorator.java:166)
    at net.minecraft.server.v1_8_R1.BiomeDecorator.a(BiomeDecorator.java:90)
    at net.minecraft.server.v1_8_R1.BiomeBase.a(SourceFile:389)
    at net.minecraft.server.v1_8_R1.ChunkProviderGenerate.getChunkAt(SourceFile:472)
    at org.bukkit.craftbukkit.v1_8_R1.generator.NormalChunkGenerator.getChunkAt(NormalChunkGenerator.java:51)
    at net.minecraft.server.v1_8_R1.ChunkProviderServer.getChunkAt(ChunkProviderServer.java:268)
    at net.minecraft.server.v1_8_R1.Chunk.loadNearby(Chunk.java:964)
    at org.bukkit.craftbukkit.v1_8_R1.chunkio.ChunkIOProvider.callStage2(ChunkIOProvider.java:68)
    at org.bukkit.craftbukkit.v1_8_R1.chunkio.ChunkIOProvider.callStage2(ChunkIOProvider.java:13)
    at org.bukkit.craftbukkit.v1_8_R1.util.AsynchronousExecutor$Task.finish(AsynchronousExecutor.java:188)
    at org.bukkit.craftbukkit.v1_8_R1.util.AsynchronousExecutor.finishActive(AsynchronousExecutor.java:347)
    at org.bukkit.craftbukkit.v1_8_R1.chunkio.ChunkIOExecutor.tick(ChunkIOExecutor.java:34)
    at net.minecraft.server.v1_8_R1.MinecraftServer.z(MinecraftServer.java:705)
    at net.minecraft.server.v1_8_R1.DedicatedServer.z(DedicatedServer.java:316)
    at net.minecraft.server.v1_8_R1.MinecraftServer.y(MinecraftServer.java:623)
    at net.minecraft.server.v1_8_R1.MinecraftServer.run(MinecraftServer.java:526)
    at java.lang.Thread.run(Unknown Source)


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

-- System Details --
Details:
    Minecraft Version: 1.8
    Operating System: Windows 8.1 (amd64) version 6.3
    Java Version: 1.8.0_25, Oracle Corporation
    Java VM Version: Java HotSpot(TM) 64-Bit Server VM (mixed mode), Oracle Corporation
    Memory: 364973136 bytes (348 MB) / 823656448 bytes (785 MB) up to 6524764160 bytes (6222 MB)
    JVM Flags: 1 total; -Xmx7000M
    IntCache: cache: 0, tcache: 0, allocated: 13, tallocated: 95
    CraftBukkit Information:
   Running: CraftBukkit version git-Spigot-8dc4297-adc129a (MC: 1.8) (Implementing API version 1.8-R0.1-SNAPSHOT) true
   Plugins: { TitleManager v1.2.1 io.puharesource.mc.titlemanager.Main [Puharesource], WorldEdit v6.0;3342-78f975b9 com.sk89q.worldedit.bukkit.WorldEditPlugin [], Essentials vTeamCity com.earth2me.essentials.Essentials [Zenexer, ementalo, Aelux, Brettflan, KimKandor, snowleo, ceulemans, Xeology, KHobbits, md_5, Iaccidentally], GroupManager v2.1.31 (Phoenix) org.anjocaido.groupmanager.GroupManager [AnjoCaido, Gabriel Couto, ElgarL], ClearLag v2.7.2 me.minebuilders.clearlag.Clearlag [bob7l], Multiverse-Core v2.5-b691 com.onarandombox.MultiverseCore.MultiverseCore [Rigby, fernferret, lithium3141, main--], InfoBoardReborn v1.0.0 com.ktar5.infoboard.InfoBoard [Ktar5], Title v1.2 me.BukkitPVP.Title.Main [BukkitPVP], EssentialsProtect vTeamCity com.earth2me.essentials.protect.EssentialsProtect [Zenexer, ementalo, Aelux, Brettflan, KimKandor, snowleo, ceulemans, Xeology, KHobbits], EssentialsChat vTeamCity com.earth2me.essentials.chat.EssentialsChat [Zenexer, ementalo, Aelux, Brettflan, KimKandor, snowleo, ceulemans, Xeology, KHobbits, md_5, Okamosy, Iaccidentally], EssentialsGeoIP vTeamCity com.earth2me.essentials.geoip.EssentialsGeoIP [Zenexer, ementalo, Aelux, Brettflan, KimKandor, snowleo, ceulemans, Xeology], EssentialsAntiBuild vTeamCity com.earth2me.essentials.antibuild.EssentialsAntiBuild [Zenexer, ementalo, Aelux, Brettflan, KimKandor, snowleo, ceulemans, Xeology, KHobbits, Iaccidentally], Multiverse-Portals v2.5-b713 com.onarandombox.MultiversePortals.MultiversePortals [Rigby, fernferret], Vault v1.5.0-b28 net.milkbowl.vault.Vault [cereal, Sleaker, mung3r], EssentialsSpawn vTeamCity com.earth2me.essentials.spawn.EssentialsSpawn [Zenexer, ementalo, Aelux, Brettflan, KimKandor, snowleo, ceulemans, Xeology, KHobbits], llamaArt v1.5 me.oooorgle.llamaArt.Main [oooorgle], Notifications v1.6 me.muizers.Notifications.Notifications [], Minigames v1.6.4 com.pauldavdesign.mineauz.minigames.Minigames [_Razz_], HolographicDisplays v2.0 com.gmail.filoghost.holographicdisplays.HolographicDisplays [], Citizens v2.0.14-SNAPSHOT (build 1195) net.citizensnpcs.Citizens [aPunch, fullwall], ChestCommands v3.0.7 com.gmail.filoghost.chestcommands.ChestCommands [], ServerSigns v3.1.0 de.czymm.serversigns.ServerSignsPlugin [CalibeR50, Exloki], CommandNPC v1.7.2 me.messageofdeath.CommandNPC.CommandNPC [messageofdeath], MinigamesLib v1.12.2 com.comze_instancelabs.minigamesapi.MinigamesAPI [InstanceLabs], MGSkyWars v1.5.1 com.comze_instancelabs.mgskywars.Main [InstanceLabs], MGSplegg v1.1.5 com.comze_instancelabs.mgsplegg.Main [InstanceLabs], MGFlyingCars v1.2.0 com.comze_instancelabs.mgflyingcars.Main [InstanceLabs], MGSnake v1.3.3 com.comze_instancelabs.mgsnake.Main [InstanceLabs],}
   Warnings: DEFAULT
   Threads: { RUNNABLE Netty Server IO #1: [sun.nio.ch.WindowsSelectorImpl$SubSelector.poll0(Native Method), sun.nio.ch.WindowsSelectorImpl$SubSelector.poll(Unknown Source), sun.nio.ch.WindowsSelectorImpl$SubSelector.access$400(Unknown Source), sun.nio.ch.WindowsSelectorImpl.doSelect(Unknown Source), sun.nio.ch.SelectorImpl.lockAndDoSelect(Unknown Source), sun.nio.ch.SelectorImpl.select(Unknown Source), io.netty.channel.nio.NioEventLoop.select(NioEventLoop.java:618), io.netty.channel.nio.NioEventLoop.run(NioEventLoop.java:306), io.netty.util.concurrent.SingleThreadEventExecutor$2.run(SingleThreadEventExecutor.java:116), java.lang.Thread.run(Unknown Source)], WAITING TimerQueue: [sun.misc.Unsafe.park(Native Method), java.util.concurrent.locks.LockSupport.park(Unknown Source), java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject.await(Unknown Source), java.util.concurrent.DelayQueue.take(Unknown Source), javax.swing.TimerQueue.run(Unknown Source), java.lang.Thread.run(Unknown Source)], TIMED_WAITING Timer-0: [java.lang.Object.wait(Native Method), java.util.TimerThread.mainLoop(Unknown Source), java.util.TimerThread.run(Unknown Source)], RUNNABLE AWT-Windows: [sun.awt.windows.WToolkit.eventLoop(Native Method), sun.awt.windows.WToolkit.run(Unknown Source), java.lang.Thread.run(Unknown Source)], TIMED_WAITING Spigot Watchdog Thread: [java.lang.Thread.sleep(Native Method), org.spigotmc.WatchdogThread.run(WatchdogThread.java:92)], TIMED_WAITING File IO Thread: [java.lang.Thread.sleep(Native Method), net.minecraft.server.v1_8_R1.FileIOThread.c(SourceFile:51), net.minecraft.server.v1_8_R1.FileIOThread.run(SourceFile:30), java.lang.Thread.run(Unknown Source)], RUNNABLE DestroyJavaVM: [], WAITING D3D Screen Updater: [java.lang.Object.wait(Native Method), sun.java2d.d3d.D3DScreenUpdateManager.run(Unknown Source), java.lang.Thread.run(Unknown Source)], RUNNABLE Netty Server IO #3: [sun.nio.ch.WindowsSelectorImpl$SubSelector.poll0(Native Method), sun.nio.ch.WindowsSelectorImpl$SubSelector.poll(Unknown Source), sun.nio.ch.WindowsSelectorImpl$SubSelector.access$400(Unknown Source), sun.nio.ch.WindowsSelectorImpl.doSelect(Unknown Source), sun.nio.ch.SelectorImpl.lockAndDoSelect(Unknown Source), sun.nio.ch.SelectorImpl.select(Unknown Source), io.netty.channel.nio.NioEventLoop.select(NioEventLoop.java:618), io.netty.channel.nio.NioEventLoop.run(NioEventLoop.java:306), io.netty.util.concurrent.SingleThreadEventExecutor$2.run(SingleThreadEventExecutor.java:116), java.lang.Thread.run(Unknown Source)], TIMED_WAITING Server Infinisleeper: [java.lang.Thread.sleep(Native Method), net.minecraft.server.v1_8_R1.ThreadSleepForever.run(SourceFile:64)], WAITING Chunk I/O Executor Thread-1: [sun.misc.Unsafe.park(Native Method), java.util.concurrent.locks.LockSupport.park(Unknown Source), java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject.await(Unknown Source), java.util.concurrent.LinkedBlockingQueue.take(Unknown Source), java.util.concurrent.ThreadPoolExecutor.getTask(Unknown Source), java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source), java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source), java.lang.Thread.run(Unknown Source)], RUNNABLE Server console handler: [org.fusesource.jansi.internal.Kernel32._getch(Native Method), org.fusesource.jansi.internal.WindowsSupport.readByte(WindowsSupport.java:46), org.bukkit.craftbukkit.libs.jline.WindowsTerminal.readByte(WindowsTerminal.java:184), org.bukkit.craftbukkit.libs.jline.WindowsTerminal.access$000(WindowsTerminal.java:53), org.bukkit.craftbukkit.libs.jline.WindowsTerminal$1.read(WindowsTerminal.java:151), java.io.FilterInputStream.read(Unknown Source), org.bukkit.craftbukkit.libs.jline.console.ConsoleReader$1.read(ConsoleReader.java:167), org.bukkit.craftbukkit.libs.jline.internal.InputStreamReader.read(InputStreamReader.java:267), org.bukkit.craftbukkit.libs.jline.internal.InputStreamReader.read(InputStreamReader.java:204), org.bukkit.craftbukkit.libs.jline.console.ConsoleReader.readCharacter(ConsoleReader.java:995), org.bukkit.craftbukkit.libs.jline.console.ConsoleReader.readLine(ConsoleReader.java:1167), net.minecraft.server.v1_8_R1.ThreadCommandReader.run(ThreadCommandReader.java:33)], WAITING pool-5-thread-1: [sun.misc.Unsafe.park(Native Method), java.util.concurrent.locks.LockSupport.park(Unknown Source), java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject.await(Unknown Source), java.util.concurrent.LinkedBlockingQueue.take(Unknown Source), java.util.concurrent.ThreadPoolExecutor.getTask(Unknown Source), java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source), java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source), java.lang.Thread.run(Unknown Source)], RUNNABLE Signal Dispatcher: [], WAITING ServerSignsQueue: [java.lang.Object.wait(Native Method), java.lang.Object.wait(Unknown Source), de.czymm.serversigns.queueSystem.QueueHandler.run(QueueHandler.java:82), java.lang.Thread.run(Unknown Source)], RUNNABLE Server thread: [java.lang.Thread.dumpThreads(Native Method), java.lang.Thread.getAllStackTraces(Unknown Source), org.bukkit.craftbukkit.v1_8_R1.CraftCrashReport.call(CraftCrashReport.java:28), net.minecraft.server.v1_8_R1.CrashReportSystemDetails.a(SourceFile:78), net.minecraft.server.v1_8_R1.CrashReport.h(CrashReport.java:43), net.minecraft.server.v1_8_R1.CrashReport.<init>(CrashReport.java:32), net.minecraft.server.v1_8_R1.MinecraftServer.run(MinecraftServer.java:546), java.lang.Thread.run(Unknown Source)], RUNNABLE Netty Server IO #0: [sun.nio.ch.WindowsSelectorImpl$SubSelector.poll0(Native Method), sun.nio.ch.WindowsSelectorImpl$SubSelector.poll(Unknown Source), sun.nio.ch.WindowsSelectorImpl$SubSelector.access$400(Unknown Source), sun.nio.ch.WindowsSelectorImpl.doSelect(Unknown Source), sun.nio.ch.SelectorImpl.lockAndDoSelect(Unknown Source), sun.nio.ch.SelectorImpl.select(Unknown Source), io.netty.channel.nio.NioEventLoop.select(NioEventLoop.java:618), io.netty.channel.nio.NioEventLoop.run(NioEventLoop.java:306), io.netty.util.concurrent.SingleThreadEventExecutor$2.run(SingleThreadEventExecutor.java:116), java.lang.Thread.run(Unknown Source)], WAITING Thread-5: [sun.misc.Unsafe.park(Native Method), java.util.concurrent.locks.LockSupport.park(Unknown Source), java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject.await(Unknown Source), java.util.concurrent.LinkedBlockingQueue.take(Unknown Source), com.mojang.util.QueueLogAppender.getNextLogEvent(QueueLogAppender.java:77), org.bukkit.craftbukkit.v1_8_R1.util.TerminalConsoleWriterThread.run(TerminalConsoleWriterThread.java:25), java.lang.Thread.run(Unknown Source)], TIMED_WAITING Snooper Timer: [java.lang.Object.wait(Native Method), java.util.TimerThread.mainLoop(Unknown Source), java.util.TimerThread.run(Unknown Source)], WAITING Java2D Disposer: [java.lang.Object.wait(Native Method), java.lang.ref.ReferenceQueue.remove(Unknown Source), java.lang.ref.ReferenceQueue.remove(Unknown Source), sun.java2d.Disposer.run(Unknown Source), java.lang.Thread.run(Unknown Source)], RUNNABLE Attach Listener: [], TIMED_WAITING pool-7-thread-1: [sun.misc.Unsafe.park(Native Method), java.util.concurrent.locks.LockSupport.parkNanos(Unknown Source), java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject.awaitNanos(Unknown Source), java.util.concurrent.ScheduledThreadPoolExecutor$DelayedWorkQueue.take(Unknown Source), java.util.concurrent.ScheduledThreadPoolExecutor$DelayedWorkQueue.take(Unknown Source), java.util.concurrent.ThreadPoolExecutor.getTask(Unknown Source), java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source), java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source), java.lang.Thread.run(Unknown Source)], WAITING Finalizer: [java.lang.Object.wait(Native Method), java.lang.ref.ReferenceQueue.remove(Unknown Source), java.lang.ref.ReferenceQueue.remove(Unknown Source), java.lang.ref.Finalizer$FinalizerThread.run(Unknown Source)], RUNNABLE Netty Server IO #2: [sun.nio.ch.WindowsSelectorImpl$SubSelector.poll0(Native Method), sun.nio.ch.WindowsSelectorImpl$SubSelector.poll(Unknown Source), sun.nio.ch.WindowsSelectorImpl$SubSelector.access$400(Unknown Source), sun.nio.ch.WindowsSelectorImpl.doSelect(Unknown Source), sun.nio.ch.SelectorImpl.lockAndDoSelect(Unknown Source), sun.nio.ch.SelectorImpl.select(Unknown Source), io.netty.channel.nio.NioEventLoop.select(NioEventLoop.java:618), io.netty.channel.nio.NioEventLoop.run(NioEventLoop.java:306), io.netty.util.concurrent.SingleThreadEventExecutor$2.run(SingleThreadEventExecutor.java:116), java.lang.Thread.run(Unknown Source)], WAITING Reference Handler: [java.lang.Object.wait(Native Method), java.lang.Object.wait(Unknown Source), java.lang.ref.Reference$ReferenceHandler.run(Unknown Source)],}
   Recent tasks from 5235-5265{Essentials:com.earth2me.essentials.EssentialsPlayerListener$1@821,}
    Profiler Position: N/A (disabled)
    Player Count: 2 / 5; [EntityPlayer['XpassElite132'/355, l='Minigames', x=208.01, y=114.00, z=145.04](XpassElite132 at 208.00643156289377,114.0,145.03848945239938), EntityPlayer['BNSXtreme'/354, l='Minigames', x=188.93, y=117.02, z=133.05](BNSXtreme at 188.93381019039066,117.0155550727022,133.04677247582026)]
    Is Modded: Definitely; Server brand changed to 'Spigot'
    Type: Dedicated Server (map_server.txt)

Thanks if someone can help!