
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)


glyphId,
            });
          }
        } else {
          warn("cmap table has unsupported format: " + format);
          return {
            platformId: -1,
            encodingId: -1,
            mappings: [],
            hasShortCmap: false,
          };
        }
        
        mappings.sort(function (a, b) {
          return a.charCode - b.charCode;
        });
        for (i = 1; i < mappings.length; i++) {
          if (mappings[i - 1].charCode === mappings[i].charCode) {
            mappings.splice(i, 1);
            i--;
          }
        }
        return {
          platformId: potentialTable.platformId,
          encodingId: potentialTable.encodingId,
          mappings,
          hasShortCmap,
        };
      }
      function sanitizeMetrics(