crash

---- Minecraft Crash Report ----
// I just don't know what went wrong :(

Time: 09/10/16 08:50
Description: Exception ticking world entities

java.lang.NullPointerException: Exception ticking world entities
	at net.minecraft.item.ItemStack.func_77977_a(ItemStack.java:441)
	at net.minecraft.entity.item.EntityItem.func_70005_c_(EntityItem.java:480)
	at mcp.mobius.mobiuscore.monitors.MonitoredEntityList.getName(MonitoredEntityList.java:50)
	at mcp.mobius.mobiuscore.monitors.MonitoredEntityList.removeCount(MonitoredEntityList.java:35)
	at mcp.mobius.mobiuscore.monitors.MonitoredList.removeAll(MonitoredList.java:63)
	at net.minecraft.world.World.func_72939_s(World.java:2430)
	at net.minecraft.world.WorldServer.func_72939_s(WorldServer.java:673)
	at net.minecraft.server.MinecraftServer.func_71190_q(MinecraftServer.java:986)
	at net.minecraft.server.dedicated.DedicatedServer.func_71190_q(DedicatedServer.java:432)
	at net.minecraft.server.MinecraftServer.func_71217_p(MinecraftServer.java:841)
	at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:693)
	at java.lang.Thread.run(Thread.java:745)