
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)


for (i = 0, j = itemSize; i < numGlyphs; i++, j += itemSize) {
          var glyphProfile = sanitizeGlyph(
            oldGlyfData,
            locaEntries[i].offset,
            locaEntries[i].endOffset,
            newGlyfData,
            writeOffset,
            hintsValid
          );
          var newLength = glyphProfile.length;
          if (newLength === 0) {
            missingGlyphs[i] = true;
          }
          if (glyphProfile.sizeOfInstructions > maxSizeOfInstructions) {
            maxSizeOfInstructions = glyphProfile.sizeOfInstructions;
          }
          writeOffset += newLength;
          itemEncode(locaData, j, writeOffset);
        }
        if (writeOffset === 0) {
          
          
          var simpleGlyph = new Uint8Array([
            0,
            1,
            0,
            0,
            0,
            0,
            0,