
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)


info(
            "Attempting to fix invalid indexToLocFormat in head table: " +
              indexToLocFormat
          );
          
          
          
          
          
          
          
          
          
          var numGlyphsPlusOne = numGlyphs + 1;
          if (locaLength === numGlyphsPlusOne << 1) {
            
            data[50] = 0;
            data[51] = 0;
          } else if (locaLength === numGlyphsPlusOne << 2) {
            
            data[50] = 0;
            data[51] = 1;
          } else {
            throw new FormatError(
              "Could not fix indexToLocFormat: " + indexToLocFormat
            );
          }
        }
      }
      function sanitizeGlyphLocations(