Bukkit

What steps will reproduce the problem?
1. Create a Tomb
2. Wait

What is the expected output? What do you see instead?
Plugin is throwing an endless stream of errors to console, all "Task 9"

What version of the product are you using?
Craftbukkit git-Bukkit-1.4.7-R1.0-b2624jnks
DeathTPPlus v3.9.16.2320

Do you have an error log of what happened?
2013-03-28 16:51:22 [WARNING] [DeathTpPlus] Task #9 for DeathTpPlus v3.9.16.2320 generated an exception
java.lang.NullPointerException
    at org.bukkit.craftbukkit.v1_4_R1.inventory.CraftInventory.getSize(CraftInventory.java:39)
    at org.bukkit.craftbukkit.v1_4_R1.inventory.CraftInventory.getContents(CraftInventory.java:52)
    at org.simiancage.DeathTpPlus.workers.TombStoneWorkerDTP.run(TombStoneWorkerDTP.java:50)
    at org.bukkit.craftbukkit.v1_4_R1.scheduler.CraftTask.run(CraftTask.java:53)
    at org.bukkit.craftbukkit.v1_4_R1.scheduler.CraftScheduler.mainThreadHeartbeat(CraftScheduler.java:344)
    at net.minecraft.server.v1_4_R1.MinecraftServer.r(MinecraftServer.java:530)
    at net.minecraft.server.v1_4_R1.DedicatedServer.r(DedicatedServer.java:224)
    at net.minecraft.server.v1_4_R1.MinecraftServer.q(MinecraftServer.java:494)
    at net.minecraft.server.v1_4_R1.MinecraftServer.run(MinecraftServer.java:427)
    at net.minecraft.server.v1_4_R1.ThreadServerApplication.run(SourceFile:849)

this repeat endlessly

Please provide any additional information below.