2012-05-19 22:36:59 [WARNING] Failed to handle packet: java.lang.NullPointerException
java.lang.NullPointerException
at net.minecraft.server.World.mayPlace(World.java:2495)
at net.minecraft.server.ItemBlock.a(ItemBlock.java:71)
at net.minecraft.server.ItemStack.placeItem(ItemStack.java:83)
at net.minecraft.server.ItemInWorldManager.interact(ItemInWorldManager.java:326)
at net.minecraft.server.NetServerHandler.a(NetServerHandler.java:616)
at net.minecraft.server.Packet15Place.handle(SourceFile:39)
at net.minecraft.server.NetworkManager.b(NetworkManager.java:231)
at net.minecraft.server.NetServerHandler.a(NetServerHandler.java:101)
at net.minecraft.server.NetworkListenThread.a(NetworkListenThread.java:78)
at net.minecraft.server.MinecraftServer.w(MinecraftServer.java:543)
at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:441)
at net.minecraft.server.ThreadServerApplication.run(SourceFile:465)

Then kicks player

Nothing in that code block is related to PreciousStones.