I wrote a small mod that added only 2 items and one entity but although it seemed to work fine, we are repeatedly crashing on a survival server I set up which is running this mod. The stack trace makes absolutely no reference to any forge/fml/mod files, and the methods deobfuscate into an NPE while rendering the player's hand; I have had nothing to do with this code.

 

java.lang.NullPointerException: Unexpected error
at net.minecraft.client.renderer.ItemRenderer.func_78440_a(ItemRenderer.java:319) [renderItemInFirstPerson]
at net.minecraft.client.renderer.EntityRenderer.func_78476_b(EntityRenderer.java:762)
at net.minecraft.client.renderer.EntityRenderer.func_175068_a(EntityRenderer.java:1402)
at net.minecraft.client.renderer.EntityRenderer.func_78471_a(EntityRenderer.java:1229)
at net.minecraft.client.renderer.EntityRenderer.func_181560_a(EntityRenderer.java:1038)
at net.minecraft.client.Minecraft.func_71411_J(Minecraft.java:1072)
at net.minecraft.client.Minecraft.func_99999_d(Minecraft.java:366)
at net.minecraft.client.main.Main.main(SourceFile:124)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at net.minecraft.launchwrapper.Launch.launch(Launch.java:135)
at net.minecraft.launchwrapper.Launch.main(Launch.java:28)

 

Looking at the report, none of the loaded entities at the time were my added entity. I also went around the world a bit in my dev environment to try to reproduce the crash but to no avail: I still have no idea what caused it.

Which line is

ItemRenderer.java:319

?