MC 1.12.2
Forge 2705
Actually Additions 1.12.2-r136-hotfix5

If you have an Immersive Engineering hemp plant inside the area that a Farmer scans, it will crash the server with the following error:
https://pastebin.com/D4DcSZjf

I haven't tested single player but will do so if needed.

Ah, yeah, the API changed. This is a beta for a reason. Go ahead and roll back to r135 in the meantime.
@BluSunrize can you update your farmer support? The changes were minimal, pretty much just removing the simulate bool and splitting into two methods.

Thank you very much!

Opening a PR to IE for this.