Resolves: fdo#76802 error msg in Web Page Wizard dialog

Change-Id: I0fa0537a8726bbda182dea8c3a9014d77973edea
Reviewed-on: https://gerrit.libreoffice.org/8797
Reviewed-by: Caolán McNamara <caolanm@redhat.com>
Tested-by: Caolán McNamara <caolanm@redhat.com>