Thanks @rjuju!

thanks for merging!

No problem. fwiw, this comment mentions using NIL, but Postgres itself uses NULL.

Yes it's not surprising, using NULL is quite strong muscle memory thing in C and the additional cast done by NIL doesn't really add much. It's definitely not a game changer to use NIL here, but if one day this list is changed to another structure (I think this kind of change happened quite frequently on the partitioning related structures some years ago) you should then get a clear compiler error rather than random errors and segfaults that will make waste a bit of time at the time it breaks. I guess that's the main reason to prefer NIL.