look for places we are doing code like:

    Reference<XProperty>(model, css::uno::UNO_QUERY)->getAsProperty()

which might result in a SIGSEGV is the query fails

Change-Id: I5cbdbc9e64bd0bed588297c512bf60cbacb9442e
Reviewed-on: https://gerrit.libreoffice.org/69044
Tested-by: Jenkins
Reviewed-by: Noel Grandin <noel.grandin@collabora.co.uk>