Thats a common problem, occurs in game world when you mess with forge or other workstation mods (Change, delete and etc.).
In my expirience this bug usualy treated by mashung 'e or esc' on forge to forcibly close the console, and then again open forge (Or simply destroy forge and replace it with new if you dont care about stuff in it).
If that does not help - try delete (temporarily) any mods which replace the forge code and try listed above again.
If that does not help again - congratultions, your world data is corrupted, create a new world.