Minecraft Version

1.12.2

Forge Version

14.23.5.2846

Mod Version

1.12.2-0.11.10-385

Describe your problem, including steps to reproduce it

Put on a pneumatic helmet, game hangs then crashes.

Any other comments?

https://pastebin.com/SfSpQJrN
I've attached the Twitch modpack I use to this. This crash happens on a 1.12.2 server.
this was the wrong file, see below

This definitely falls under the "should never happen" and also the "I can't reproduce it" categories.

I can add an easy workaround to prevent that crash, but I have no idea why the method in question is returning null at the point in your crash, and makes me wonder what is wrong elsewhere...

Can you try build 387+ from https://jenkins.k-4u.nl/job/PneumaticCraft-Repressurized/ and let me know if that helps?

Uploading mod to multiplayer server now, will have answers in about 30 minutes.

D'OH... I gave you the wrong pack. So sorry about that...
https://drive.google.com/open?id=1E__dVg9CB8-zARvPyL9yxAKblubpDsjI

Okay, I can now put the helmet on. However no GUI is shown and when settings are accessed the entire game freezes, then crashes.
https://pastebin.com/WH8tNySV

I honestly don't know what's going on there. Clearly something's badly broken, but I can't reproduce the problem, and I can't see how it would happen either. I'll continue to investigate though.

Update: actually, one possibility - some other mod is cancelling the GuiScreenEvent.InitGuiEvent.Pre event. That would prevent the helmet GUI init code running, which would in turn cause those crashes you're seeing (no upgrade handler components added).

I've just pushed another change, so can you give build 388 a go when you get a chance?

Hopefully fixed in 0.11.11 release