CRASH MCREATOR on coding

Hi, i'm creating a simple mod, and i needed to edid the code myself, i access the code from the internal editor, but when i try to create a 

NonNullList<ItemStack> 

The software crash... 

In particular, after 1 second, I type the for the "ItemStack" string

sorry for my English, I'm Italian.

I use linux (pop os 21.04)

error is:

log:

https://www.toptal.com/developers/hastebin/ocidiwajaw.makefile