Don't show a critical warning on invalid yaml file
Don't show a critical warning on invalid yaml file

This is surely invalid, but we should do better than a critical:

    Categories:
      - ''

ximion/appstream-glib,hughsie/appstream-glib,hughsie/appstream-glib,ximion/appstream-glib,hughsie/appstream-glib,ximion/appstream-glib