
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)


const ttcTag = bytesToString(ttc.getBytes(4));
        assert(ttcTag === "ttcf", "Must be a TrueType Collection font.");
        const majorVersion = ttc.getUint16();
        const minorVersion = ttc.getUint16();
        const numFonts = ttc.getInt32() >>> 0;
        const offsetTable = [];
        for (let i = 0; i < numFonts; i++) {
          offsetTable.push(ttc.getInt32() >>> 0);
        }
        const header = {
          ttcTag,
          majorVersion,
          minorVersion,
          numFonts,
          offsetTable,
        };
        switch (majorVersion) {
          case 1:
            return header;
          case 2:
            header.dsigTag = ttc.getInt32() >>> 0;
            header.dsigLength = ttc.getInt32() >>> 0;
            header.dsigOffset = ttc.getInt32() >>> 0;
            return header;
        }
        throw new FormatError(
          `Invalid TrueType Collection majorVersion: ${majorVersion}.`
        );
      }
      function readTrueTypeCollectionData(ttc, fontName) {