
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)


var glyphNameIndexes = [];
            for (i = 0; i < numGlyphs; ++i) {
              var index = font.getUint16();
              if (index >= 32768) {
                valid = false;
                break;
              }
              glyphNameIndexes.push(index);
            }
            if (!valid) {
              break;
            }
            var customNames = [];
            var strBuf = [];
            while (font.pos < end) {
              var stringLength = font.getByte();
              strBuf.length = stringLength;
              for (i = 0; i < stringLength; ++i) {
                strBuf[i] = String.fromCharCode(font.getByte());
              }
              customNames.push(strBuf.join(""));
            }
            glyphNames = [];
            for (i = 0; i < numGlyphs; ++i) {
              var j = glyphNameIndexes[i];
              if (j < 258) {
                glyphNames.push(MacStandardGlyphOrdering[j]);
                continue;
              }
              glyphNames.push(customNames[j - 258]);