Yes, you are right. Empty lists were causing trouble. They shouldn’t however, should they?
I would also like to conclude on the nulls described in post 7:
after rebooting my computer this error did not consist.
This reminded me of another annoying DynamoCivil bug that I found can be solved by rebooting:
disappearing nodes. See for example:
A lot of work needs to be done to make Dynamo for Civil more stable!