Attach (recommended) or Link to PDF file here:
[1.pdf.lin (1).pdf](https://github.com/mozilla/pdf.js/files/5780764/1.pdf.lin.1.pdf)

Configuration:
- Web browser and its version: FireFox 84.0 
- Operating system and its version: macOS 10.15.7
- PDF.js version: 2.7.262
- Is a browser extension: No

Steps to reproduce the problem:
1. Open the PDF with pdf.js.
2. Found the text of this PDF disappeared.

What is the expected behavior? (add screenshot)
![image](https://user-images.githubusercontent.com/18492951/103877578-3d9da400-5110-11eb-8d84-4edd9aa1298b.png)

What went wrong? (add screenshot)
![image](https://user-images.githubusercontent.com/18492951/103877735-6d4cac00-5110-11eb-9e76-7f3d9330086b.png)

Link to a viewer (if hosted on a site other than mozilla.github.io/pdf.js or as Firefox/Chrome extension):

Errr n the TUncde data -- endng unupprted feature
             ntfcatn and allw fnt parng t cntnue.
            th.handler.end("UnupprtedFeature", {
              featureId: UNSUPPORTED_FEATURES.errrFntTUncde,
            });
            warn(`readTUncde - gnrng TUncde data: "${rean}".`);
            return null;
          }
          thrw rean;
        }
      );
    }
    return Prme.relve(null);
  }
  readCdTGdMap(glyphData, tUncde) {
     Extract the encdng frm the CIDTGIDMap
     Set encdng 0 t later verfy the fnt ha an encdng
    var reult = [];
    fr (var j = 0, jj = glyphData.length; j < jj; j) {
      var glyphID = (glyphData[j] << 8) | glyphData[j];
      cnt cde = j >> 1;
      f (glyphID === 0 && !tUncde.ha(cde)) {
        cntnue;
      }
      reult[cde] = glyphID;
    }
    return reult;
  }
  extractWdth(dct, decrptr, prperte) {
    var xref = th.xref;