Problem Servercrashes again and again

[peterswo]

I dont know what i do wrong, the Server crashes again and again

what can i fix


---- Minecraft Crash Report ----
// This doesn't make any sense!

Time: 12/9/14 1:54 PM
Description: Exception in server tick loop

java.lang.NullPointerException
at codechicken.lib.world.WorldExtensionManager.postTick(WorldExtensionManager.java:245)
at codechicken.lib.world.WorldExtensionManager.access$500(WorldExtensionManager.java:25)
at codechicken.lib.world.WorldExtensionManager$WorldExtensionServerTickHandler.tickEnd(WorldExtensionManager.java:169)
at cpw.mods.fml.common.SingleIntervalHandler.tickEnd(SingleIntervalHandler.java:34)
at cpw.mods.fml.common.FMLCommonHandler.tickEnd(FMLCommonHandler.java:141)
at cpw.mods.fml.common.FMLCommonHandler.onPostWorldTick(FMLCommonHandler.java:282)
at net.minecraft.server.MinecraftServer.func_71190_q(MinecraftServer.java:677)
at net.minecraft.server.dedicated.DedicatedServer.func_71190_q(DedicatedServer.java:276)
at net.minecraft.server.MinecraftServer.func_71217_p(MinecraftServer.java:587)
at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:484)
at net.minecraft.server.ThreadMinecraftServer.run(SourceFile:583)