fix issue #817 (ot-sanitize crashes when exit code is non-zero)
fix issue #817 (ot-sanitize crashes when exit code is non-zero)

googlefonts/fontbakery,graphicore/fontbakery,graphicore/fontbakery,googlefonts/fontbakery,graphicore/fontbakery,moyogo/fontbakery,moyogo/fontbakery,moyogo/fontbakery,googlefonts/fontbakery