hello daz96050
thanks for making a good mod :)
This happened while constructing a ghost building using copy and paste in the Factoryissimo factory.
https://mods.factorio.com/mod/factorissimo-2-notnotmelon

Error while running event Construction_Drones_Forked::on_script_path_request_finished (ID 134)
Unknown item name: one-to-two-parallel-pipe
stack traceback:
[C]: in function 'insert'
Construction_Drones_Forked/script/command_processor.lua:644: in function <Construction_Drones_Forked/script/command_processor.lua:600>
(...tail calls...)
Construction_Drones_Forked/script/event_processor.lua:285: in function 'handler'
core/lualib/event_handler.lua:72: in function <core/lualib/event_handler.lua:70>

Are you on the latest version?
I don't see that code in the lines referenced in your error

This issue occurred when copying the pipe from the mod below and forcibly pasting it (holding shift) onto an existing pipe.
https://mods.factorio.com/mod/underground-pipe-pack

Yes, it is the latest version 0.1.5.

I tried to test this locally and could not reproduce the issue.
Could you upload a save somewhere where the issue is happening.

Just make the bots leave to do what is going to cause an error (preferrably a bit away from the item), and then save and upload it.

Thank you for your reply.
After reporting the error, I'm still playing fine.
Reproducing the reported situation and uploading it is not difficult.
But aside from that, I play with a lot of mods.
The number of mods is well over 700.
On my PC, it takes a little over 3 ~ 4 minutes to load.
Uploading a save file like this would be too much trouble for you to test. X)
If the error occurs while playing again, I will consider reducing the number of mods, reproducing the error, and uploading it.
Thank you, daz96050 :)