Create Floor Error

10:56:43 [INFO] mbcx2 issued server command: /spleef addfloor 1
10:56:43 [INFO] Loading floor
10:56:43 [INFO] 9 63 -12
10:56:43 [INFO] -4 63 -20
10:56:43 [INFO] 9 63 -12
10:56:43 [INFO] -4 63 -20
10:56:43 [INFO] 9 63 -12
10:56:43 [INFO] -4 63 -20
10:56:43 [INFO] 9 63 -12
10:56:43 [INFO] -4 63 -20
10:56:43 [INFO] 9 63 -12
10:56:43 [INFO] -4 63 -20
10:56:43 [INFO] Loaded 126/630 blocks into the floor of Spleef arena 1
10:56:43 [INFO] 1 Loaded floor!
10:56:43 [SEVERE] java.lang.NullPointerException
10:56:43 [SEVERE]       at org.bukkit.craftbukkit.CraftServer.getWorld(CraftServ
er.java:794)
10:56:43 [SEVERE]       at org.bukkit.Bukkit.getWorld(Bukkit.java:167)
10:56:43 [SEVERE]       at org.mcsg.double0negative.spleef.Game.loadGame(Game.ja
va:97)
10:56:43 [SEVERE]       at org.mcsg.double0negative.spleef.Game.addFloor(Game.ja
va:590)
10:56:43 [SEVERE]       at org.mcsg.double0negative.spleef.commands.AddFloor.onC
ommand(AddFloor.java:14)
10:56:43 [SEVERE]       at org.mcsg.double0negative.spleef.CommandHandler.onComm
and(CommandHandler.java:109)
10:56:43 [SEVERE]       at org.bukkit.command.PluginCommand.execute(PluginComman
d.java:44)
10:56:43 [SEVERE]       at org.bukkit.command.SimpleCommandMap.dispatch(SimpleCo
mmandMap.java:186)
10:56:43 [SEVERE]       at org.bukkit.craftbukkit.CraftServer.dispatchCommand(Cr
aftServer.java:502)
10:56:43 [SEVERE]       at net.minecraft.server.NetServerHandler.handleCommand(N
etServerHandler.java:985)
10:56:43 [SEVERE]       at net.minecraft.server.NetServerHandler.chat(NetServerH
andler.java:903)
10:56:43 [SEVERE]       at net.minecraft.server.NetServerHandler.a(NetServerHand
ler.java:858)
10:56:43 [SEVERE]       at net.minecraft.server.Packet3Chat.handle(Packet3Chat.j
ava:44)
10:56:43 [SEVERE]       at net.minecraft.server.NetworkManager.b(NetworkManager.
java:290)
10:56:43 [SEVERE]       at net.minecraft.server.NetServerHandler.d(NetServerHand
ler.java:113)
10:56:43 [SEVERE]       at net.minecraft.server.ServerConnection.b(SourceFile:39
)
10:56:43 [SEVERE]       at net.minecraft.server.DedicatedServerConnection.b(Sour
ceFile:30)
10:56:43 [SEVERE]       at net.minecraft.server.MinecraftServer.r(MinecraftServe
r.java:595)
10:56:43 [SEVERE]       at net.minecraft.server.DedicatedServer.r(DedicatedServe
r.java:222)
10:56:43 [SEVERE]       at net.minecraft.server.MinecraftServer.q(MinecraftServe
r.java:493)
10:56:43 [SEVERE]       at net.minecraft.server.MinecraftServer.run(MinecraftSer
ver.java:426)
10:56:43 [SEVERE]       at net.minecraft.server.ThreadServerApplication.run(Sour
ceFile:856)