
Attach (recommended) or Link to PDF file here:
[NAPEN16171380959.pdf](https://github.com/mozilla/pdf.js/files/6143802/NAPEN16171380959.pdf)

Configuration:
- Web browser and its version: Firefox 88 Nightly
- Operating system and its version: Windows 10
- PDF.js version:
- Is a browser extension: No

What went wrong? (add screenshot)
![](https://user-media-prod-cdn.itsre-sumo.mozilla.net/uploads/images/2021-03-15-10-58-27-ce2796.png)


codes = range[2];
        var code = codes[0];
        for (j = 1, jj = codes.length; j < jj; ++j) {
          if (codes[j] !== codes[j - 1] + 1) {
            end = range[0] + j - 1;
            format31012 +=
              string32(start) + 
              string32(end) + 
              string32(code); 
            start = end + 1;
            code = codes[j];
          }
        }
        format31012 +=
          string32(start) + 
          string32(range[1]) + 
          string32(code); 
      }
      header31012 =
        "\x00\x0C" + 
        "\x00\x00" + 
        string32(format31012.length + 16) + 
        "\x00\x00\x00\x00" + 
        string32(format31012.length / 12); 
    }
    return (
      cmap +
      "\x00\x04" + 
      string16(format314.length + 4) + 
      format314 +