peeling off a small chunk of my ErrCode strong_int conversion

Change-Id: Idc89e8496083beed7608cba705cd981139eb7111
Reviewed-on: https://gerrit.libreoffice.org/38777Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Noel Grandin <noel.grandin@collabora.co.uk>