i kept encountering this error periodically and narrowed it down to using a blueprint book
The mod Companion Drones 2.0 (2.0.5) caused a non-recoverable error.
Please report this error to the mod author.

Error while running event companion-drones::on_pre_build (ID 9)
Item is not blueprint.
stack traceback:
[C]: in function 'get_blueprint_entities'
companion-drones/script/companion.lua:1522: in function 'get_blueprint_area'
companion-drones/script/companion.lua:1579: in function 'handler'
core/lualib/event_handler.lua:47: in function <core/lualib/event_handler.lua:45>

once i took the blueprint out of the book and used it standalone it seemed to work fine

Please check version 2.0.6, I can't reproduce it in my saves

If the blueprint book contains not only blueprints but also other blueprint books - this is fixed in 2.0.7