Error in the write with the convert engine with PAM images

[gtnx]

I need to resize the following image using the convert image.

This image seems to be "peculiar" because of the output of convert:

$> convert image.jpeg -auto-orient -colorspace RGB -scale 300x51! -interlace line -quality 95 /tmp/tmpt49zq84_.jpg
Decoded /var/tmp/magick-90708E_oYRuZuEia9. Dimensions: 1186 x 200 . Format: lossy. Now saving...
Saved file /var/tmp/magick-90708Dxx1Mcb7LAfD

$> echo $?
0

The issue is that convert output those two lines on stderr. In the code, an error is raised if something is outputed on stderr. Even if the status code of the process is 0 (ok), like in the case above.

Wouldn't it make more sense to test the status code of the subprocess rather than checking if something is written on stderr?