Check for null images before attempting to scale them

This is mainly to silence runtime warnings related to that, doesn't
actually behavior.
3 jobs for master in 13 minutes and 7 seconds
Status Name Job ID Coverage
  Build
passed build_clazy_clang_tidy #98293

00:09:43

passed linux kf5-qt5 qt5.15 #98292

00:02:52

70.0%
 
  Test
passed reuse #98294

00:00:31