
The parameter used to be optional until commit d54219c098
, but
after GObjectifaction `undefined` is no longer interchangeable
with `null` here.
Restore the old behavior, as it's used by extensions (including
one of our own templates).
Closes: https://gitlab.gnome.org/GNOME/gnome-shell/-/issues/8068
Part-of: <https://gitlab.gnome.org/GNOME/gnome-shell/-/merge_requests/3548>