second attempt at fixing my asserts

it appears I can't trust the buildbots, they don't seem to be
compiling with asserts

Change-Id: Ia49f5d3f134cf1a578469ddcbc7c492383aa971d
Reviewed-on: https://gerrit.libreoffice.org/12184
Reviewed-by: Noel Grandin <noelgrandin@gmail.com>
Tested-by: Noel Grandin <noelgrandin@gmail.com>