Bukkit

08:57:11 [WARNING] [ExperienceMod] §cWarning: Error java.lang.NullPointerException occured in com                                                                                               m.comphenix.xp.listeners.ExperienceItemListener@642da0be.
08:57:11 [SEVERE]   [ExperienceMod] INTERNAL ERROR!
  If this problem has't already been reported, please open a ticket
  at http://dev.bukkit.org/server-mods/experiencemod/ with the following data:
            ===== STACK TRACE =====
  java.lang.NullPointerException
        at com.comphenix.xp.mods.StandardBlockService.processClickEvent(StandardBlockService.java:48)
        at com.comphenix.xp.mods.CustomBlockProviders.processInventoryClick(CustomBlockProviders.java:37)
        at com.comphenix.xp.listeners.ExperienceItemListener.onInventoryClickEvent(ExperienceItemListener.java:203)
        at sun.reflect.GeneratedMethodAccessor264.invoke(Unknown Source)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at java.lang.reflect.Method.invoke(Method.java:601)
        at org.bukkit.plugin.java.JavaPluginLoader$1.execute(JavaPluginLoader.java:330)
        at org.bukkit.plugin.RegisteredListener.callEvent(RegisteredListener.java:62)
        at org.bukkit.plugin.TimedRegisteredListener.callEvent(TimedRegisteredListener.java:35)
        at org.bukkit.plugin.SimplePluginManager.fireEvent(SimplePluginManager.java:477)
        at org.bukkit.plugin.SimplePluginManager.callEvent(SimplePluginManager.java:462)
        at net.minecraft.server.NetServerHandler.a(NetServerHandler.java:1109)
        at net.minecraft.server.Packet102WindowClick.handle(SourceFile:29)
        at net.minecraft.server.NetworkManager.b(NetworkManager.java:276)
        at net.minecraft.server.NetServerHandler.d(NetServerHandler.java:109)
        at net.minecraft.server.ServerConnection.b(SourceFile:35)
        at net.minecraft.server.DedicatedServerConnection.b(SourceFile:30)
        at net.minecraft.server.MinecraftServer.q(MinecraftServer.java:581)
        at net.minecraft.server.DedicatedServer.q(DedicatedServer.java:212)
        at net.minecraft.server.MinecraftServer.p(MinecraftServer.java:474)
        at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:406)
        at net.minecraft.server.ThreadServerApplication.run(SourceFile:539)
            ===== DUMP =====
  Parameters:
    org.bukkit.event.inventory.CraftItemEvent@63f974de[
      recipe=org.bukkit.craftbukkit.inventory.CraftShapedRecipe@e67ce19
      slot_type=RESULT
      rightClick=false
      shiftClick=false
      result=DEFAULT
      whichSlot=0
      rawSlot=0
      current=<null>
      transaction=org.bukkit.craftbukkit.inventory.CraftInventoryView@2969ac02
      name=<null>
      async=false
    ]
    [NULL]
    [NULL]
    rewardProvider:
      com.comphenix.xp.rewards.RewardProvider@5c91e71f[
        configuration=<null>
        nameLookup={DROPS=com.comphenix.xp.rewards.items.RewardDrops@63cec5a1, EXPERIENCE=com.comphenix.xp.rewards.xp.RewardExperience@1c110038, VIRTUAL=com.comphenix.xp.rewards.xp.RewardVirtual@20256aed, ECONOMY=com.comphenix.xp.rewards.xp.RewardEconomy@788efe17}
        disabledLookup=[]
        defaultName=VIRTUAL
      ]
    channelProvider:
      com.comphenix.xp.messages.ChannelProvider@4b440ffe[
        defaultChannels=[global]
        messageFormatter=com.comphenix.xp.messages.MessageFormatter@6176134c
        nameLookup={STANDARD=com.comphenix.xp.messages.StandardService@fb61571}
        disabledLookup=[]
        defaultName=STANDARD
      ]
    historyProvider:
      com.comphenix.xp.history.HistoryProviders@9ccd7b7[
        nameLookup={HAWKEYE=com.comphenix.xp.history.HawkeyeService@67663467, MEMORY=com.comphenix.xp.history.MemoryService@66fa8b39, LOGBLOCK=com.comphenix.xp.history.LogBlockService@4aca8000}
        disabledLookup=[]
        defaultName=LOGBLOCK
      ]
    customProvider:
      com.comphenix.xp.mods.CustomBlockProviders@5378fcfe[
        lastInteraction=com.comphenix.xp.listeners.PlayerInteractionListener@2c29b282
        nameLookup={STANDARD=com.comphenix.xp.mods.StandardBlockService@65868b74}
        disabledLookup=[]
        defaultName=STANDARD
      ]
  Sender:
    com.comphenix.xp.listeners.ExperienceItemListener@642da0be[
      debugger=ExperienceMod v2.4.0
      scheduler=com.comphenix.xp.PlayerScheduler@6f944d53
      blockProvider=com.comphenix.xp.mods.CustomBlockProviders@5378fcfe
      random=java.util.Random@7160bd5f
      report=com.comphenix.xp.listeners.ErrorReporting@630e220
      presets=com.comphenix.xp.Presets@6ed098f7
    ]

After a while this leads to a maximum of errors, unable to run the mod after that, keeps spamming error lines.

I'm unable to reproduce this problem, but looking at the error dump I'd say it's either caused by severe lag or a change in the most recent version(s) of CraftBukkit.

Could it be that this error occurs when you trade with merchants/villagers? Or when you craft items in your own inventory screen?

Still, while I don't know exactly what's causing this, I know a simple fix. I've uploaded a nightly build with this fix on GitHub:
https://github.com/downloads/aadnk/ExperienceMod/ExperienceMod%20-%20NIGHTLY%20150812a.zip

Please let me know if this version resolves the prioblem.

aadnk.

Lag wouldn't be too logical, at least TPS was over 15 at the time.

Our villager trading is disabled as it's broken unbalanced overpowerd crap :>

Inventory actions are implied by the error, but I wouldn't know what, players do as they please :P Not running Tekkit or anything though.

Will try the nightly build tomorrow.

Tested your fixed version, sadly it still spams those inventory errors.

@Joymo: Go

That shouldn't even be possible. Strange - could you post the error report you get after using the nightly build? While it may be a NullPointerException, it's hard to believe it would occur at the same place.

Also, what plugins are you using? Maybe the problem occurs with a certain plugin.

aadnk.

I have the same problem. It happens like 30x per day. Would help if I post my report as well?

@RafaSKB: Go

Sure, go ahead. It's certainly better if don't miss anything before I push out the next version. :)