I get this crash randomly while playing. https://pastebin.com/MhwTuvxt
I already reported it to Buildcraft devs, but they told me it was caused by NEI. BuildCraft/BuildCraft#3639
I use Minecraft 1.11.2, Forge 13.20.0.2310

Here stack can be null, and then this null passed to RenderTooltipEvent.PostText event, which has @Nonnull near stack field.

Ahhh, cheers for catching that. Will hopefully get something out later on fixing all the things, want to finish up some of the new fmp api first.