code: def com_google_fonts_check_fontforge_stderr(font, fontforge_check_results):
    
    if "skip" in fontforge_check_results:
      yield SKIP, fontforge_check_results["skip"]
      return
  
    filtered_err_msgs = ""
    for line in fontforge_check_results["ff_err_messages"].split('\n'):
      if ('The following table(s) in the font'
          ' have been ignored by FontForge') in line:
        continue
      if "Ignoring 'DSIG' digital signature table" in line:
        continue
      filtered_err_msgs += line + '\n'
  
    if len(filtered_err_msgs.strip()) > 0:
      yield WARN, ("FontForge seems to dislike certain aspects of this font file."
                   " The actual meaning of the log messages below is not always"
                   " clear and may require further investigation.\n\n"
                   "{}").format(filtered_err_msgs)
    else:
      yield PASS, "FontForge validation did not output any error message."
docs: FontForge validation outputs error messages?