fix `OWNPV_NDOF` and update for Rec!4079
F.OWNPV may return a nullptr, and thus anything downstream of it may be an optional - so add F.VALUE_OR to deal with that.
required for Rec!4079 (merged) (and this also contains an update for a change in the generated C++ code for functors introduced in that MR, so must be applied at the same time)
Edited by Gerhard Raven