Unfortunately that's not telling me which trait it is... Can you send over the "Full Error Callstack"?
Viewing post in Premade Sim and Relationship Overhaul comments
The second error appears to be having the Vampires pack active and not having a second, unspecified pack. I'll dig in and see which pack that might be. Thank you for your help!
Edit: it appears the culprit is Growing Together. Several traits got moved to that pack unexpectedly. Why, I do not know, since they shouldn't be in there. But I will have a fix go live tomorrow.