Narrowed down the source of this issue (At least for me) and I suppose happily it's with the mod I was thinking of swapping out to something less potent.
The conflict (At least the one I experienced) is between this and the Dark Matter 0.17 port, which in retrospect makes some sense with the error revived, and it's the only mod whose internal lua I've had to poke at before. Dark Matter indexes other techs and recipes to establish replication recipes and techs so I imagine that's what triggers this indexing '?' field.
Hope that's of some assistance - Ideally in the future I'd mess about with both at the same time.
