I think I know that correction log error trap messages can safely be ignored except possibly if there's mystery maladies, in which case they might indicate that something is off with a script somewhere. I tend to think the same is true for null value error trap messages, but less so. I mean: a null value isn't a measure of pathology in the absence of obvious trouble, but if there's trouble, it might help to pinpoint what it is?

So if, for example, I haven't ever entered live mod in this new game because I'm busy building the neighborhood, and an interactive modded object like lyralei's sheep throws a bunch of identical null value error mods before it's even placed, I can ignore it till I enter live mode? & if it continues to throw errors of this type, and the live mode exhibits trouble, I would attempt to understand it then?

(I have also sent a question to lyralei att MTS of course)

If you get any type of error it's not normal behavior and shouldn't be ignored. Scripting is meant to complete without erroring. If it's not then it should be looked at. However since it's Lyralei's mod then of course the best thing to do is to ask them about the issue.

I did ask Lyralei about it. She had gotten other questions about it, but she can't reproduce it. So we had a conversation about everything I could notice, and she thinks she may have found where it is. She doesn't think it's dangerous for the game in the meantime but she intends to fix it.