
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 newMap = Object.create(null);
    var toFontChar = [];
    var privateUseAreaIndex = 0;
    var nextAvailableFontCharCode = PRIVATE_USE_AREAS[privateUseAreaIndex][0];
    var privateUseOffetEnd = PRIVATE_USE_AREAS[privateUseAreaIndex][1];
    for (var originalCharCode in charCodeToGlyphId) {
      originalCharCode |= 0;
      var glyphId = charCodeToGlyphId[originalCharCode];
      
      
      if (!hasGlyph(glyphId)) {
        continue;
      }
      if (nextAvailableFontCharCode > privateUseOffetEnd) {
        privateUseAreaIndex++;