I'm sorry but I don't remember where that one came from. It appeared to be caused by the oviposition fetish variable in the person object being NIL (error basically said it was comparing a STRING to a NIL in an IF statement) . But looking at person.gd I see you are defining that variable as "none" when it is created. So unless the code overwrites the "none" value with NIL at some point I'm not sure what the root cause might be. Is the value reset to NIL when you ask them about the fetish and they refuse to talk about it (the whole "Eww I can't talk about that")?
I also have to compliment you on how responsive you are to bugs. I'm a software developer and I'm not always this responsive to my users LOL. Anyways, great job.