Error while running event companion-drones::on_pre_build (ID 9)
LuaItemStack doesn't contain key contents.
stack traceback:
[C]: in function 'index'
__companion-drones/script/companion.lua:1529: in function 'get_all_blueprint_entities'
companion-drones/script/companion.lua:1555: in function 'get_blueprint_area'
companion-drones/script/companion.lua:1588: in function 'handler'
core/lualib/event_handler.lua:47: in function <core/lualib/event_handler.lua:45>

just pasting some defense (around 1000 walls), had 20 drones with me at the time

I am getting a similar error while trying to put in a blueprint.
At first, I thought it was that the blueprint had items that I had not learned, but I attempted another one with items that I knew I had. It errored out. The ones I was using are older blueprints so not sure if that has something to do with it.

Fixed in 2.0.9