Do not silence warnings when rendering the page with PS backend
From Atril's PR https://github.com/mate-desktop/atril/pull/507
Without checking result status (silencing warning):
$ atril ~/Documents/ptc40.ps
(libspectre) ghostscript reports: undefined -21
Segmentation fault (core dumped)
After checking the status:
$ atril ~/Documents/ptc40.ps (libspectre) ghostscript reports: undefined -21
** (atril:325985): WARNING **: 21:08:44.687: libspectre reports: render error Segmentation fault (core dumped)