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


const map = this._map;
      if (map.length <= 0x10000) {
        return map.indexOf(value);
      }
      for (const charCode in map) {
        if (map[charCode] === value) {
          return charCode | 0;
        }
      }
      return -1;
    },
    amend(map) {
      for (var charCode in map) {
        this._map[charCode] = map[charCode];
      }
    },
  };
  return ToUnicodeMap;
})();
var IdentityToUnicodeMap = (function IdentityToUnicodeMapClosure() {
  
  function IdentityToUnicodeMap(firstChar, lastChar) {
    this.firstChar = firstChar;
    this.lastChar = lastChar;
  }
  IdentityToUnicodeMap.prototype = {
    get length() {