17:05:32 [SEVERE] java.lang.NullPointerException
17:05:32 [SEVERE]       at net.minecraft.server.WorldData.a(WorldData.java:128)
17:05:32 [SEVERE]       at net.minecraft.server.WorldData.a(WorldData.java:122)
17:05:32 [SEVERE]       at net.minecraft.server.WorldNBTStorage.saveWorldData(Wo
rldNBTStorage.java:124)
17:05:32 [SEVERE]       at net.minecraft.server.ServerNBTManager.saveWorldData(S
ourceFile:43)
17:05:32 [SEVERE]       at net.minecraft.server.World.y(World.java:279)
17:05:32 [SEVERE]       at net.minecraft.server.World.save(World.java:268)
17:05:32 [SEVERE]       at net.minecraft.server.World.doTick(World.java:1739)
17:05:32 [SEVERE]       at net.minecraft.server.MinecraftServer.w(MinecraftServe
r.java:521)
17:05:32 [SEVERE]       at net.minecraft.server.MinecraftServer.run(MinecraftSer
ver.java:432)
17:05:32 [SEVERE]       at net.minecraft.server.ThreadServerApplication.run(Sour
ceFile:465)
17:05:32 [SEVERE] Unexpected exception
java.lang.NullPointerException
        at net.minecraft.server.WorldData.a(WorldData.java:128)
        at net.minecraft.server.WorldData.a(WorldData.java:122)
        at net.minecraft.server.WorldNBTStorage.saveWorldData(WorldNBTStorage.ja
va:124)
        at net.minecraft.server.ServerNBTManager.saveWorldData(SourceFile:43)
        at net.minecraft.server.World.y(World.java:279)
        at net.minecraft.server.World.save(World.java:268)
        at net.minecraft.server.World.doTick(World.java:1739)
        at net.minecraft.server.MinecraftServer.w(MinecraftServer.java:521)
        at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:432)
        at net.minecraft.server.ThreadServerApplication.run(SourceFile:465)
>