tools/gegl-imgcmp: fail if no output image
This is the patch from: https://bugzilla.gnome.org/show_bug.cgi?id=792692
I have turned it into a merge request to prevent it from getting lost.
This is the patch from: https://bugzilla.gnome.org/show_bug.cgi?id=792692
I have turned it into a merge request to prevent it from getting lost.