
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)


segment = segments[segIndex];
            start = segment.start;
            var end = segment.end;
            var delta = segment.delta;
            offsetIndex = segment.offsetIndex;
            for (j = start; j <= end; j++) {
              if (j === 0xffff) {
                continue;
              }
              glyphId = offsetIndex < 0 ? j : offsets[offsetIndex + j - start];
              glyphId = (glyphId + delta) & 0xffff;
              mappings.push({
                charCode: j,
                glyphId,
              });
            }
          }
        } else if (format === 6) {
          
          
          
          
          
          var firstCode = file.getUint16();
          var entryCount = file.getUint16();
          for (j = 0; j < entryCount; j++) {
            glyphId = file.getUint16();
            var charCode = firstCode + j;
            mappings.push({
              charCode,