https://mods.factorio.com/mods/DaveMcW/blueprint-string/discussion/1147

Same bug, just follow the URL.

Error message for killkrog:
Error while running the event handler: KBlueprints/control.lua:611: Given index value is too big, the data type allows values from 0 to 255

Do you use inventory size mods?
Factorio only uses one byte (0-255) to index your inventory.
Having a larger inventory will cause this bug when searching your inventory for an item, like an empty blueprint/blueprint book in this case.
There is no way to prevent that, it's just how Factorio was built.

Fixed in Factorio 0.13.12. More info from link in OP.