re-arrange the logic so that when create_doc_in_start_center fails, we
only get one backtrace instead of two.

Change-Id: I736b56da8cfb11e8ef17b8422a19eafd70e3cd6f
Reviewed-on: https://gerrit.libreoffice.org/66415
Tested-by: Jenkins
Reviewed-by: Noel Grandin <noel.grandin@collabora.co.uk>