No code in it, red input: blueprint-book = 1 at the time. Deleted it and used Undo, with instant blueprints from Creative Mod. Then opened the gui.
It's deprecated, but still updated. And I'm back to Factorio trying to pick up my self expanding factory project again and this is what I used before. I guess I could port to LC3, I guess I'll do that soonish.

<3

The mod LuaCombinator 2 (0.18.27) caused a non-recoverable error.
Please report this error to the mod author.
Error while running event LuaCombinator2::on_gui_opened (ID 84)
LuaCombinator2/control.lua:1121: attempt to index field '?' (a nil value)
stack traceback:
LuaCombinator2/control.lua:1121: in function 'create_gui'
LuaCombinator2/control.lua:1063: in function <LuaCombinator2/control.lua:1054>