Sometimes, several seconds after I remove a farm building with deconstruction planner I get this error:
Error while running event pyalienlife::on_nth_tick(121)
pyalienlife/scripts/farming/farming.lua:85: attempt to index local 'farm' (a nil value)
stack traceback:
pyalienlife/scripts/farming/farming.lua:85: in function <pyalienlife/scripts/farming/farming.lua:80>

It seems this can happen with any of the farm buildings. Disabling and enabling AlienLife mode fixes this error until it happens again with another farm.

Yes,the same error happened to mine.I tried removing the farm after removing all the items from the device,and it seemed to succeed.But I don't know if it's useful for everyone.

This is fixed on github. It will be resolved in the next update. Thanks for the report.