Attach (recommended) or Link to PDF file here:
[example.pdf](https://github.com/mozilla/pdf.js/files/6916129/example.pdf)

Configuration:
- Web browser and its version: Chrome, Firefox
- Operating system and its version: all
- PDF.js version: various versions, including 2.11.54
- Is a browser extension: no

Screenshot with visible textLayer:
![Screenshot from 2021-08-02 13-05-03](https://user-images.githubusercontent.com/6362989/127844878-f85e291f-2060-4028-be09-7835f32ccfaa.png)

Which means some letters at the beginning/end of text selection are missing when copying text.

d: ptnalCntentGrup.tStrng(),
        };
      }
    }
    return null;
  }
  getOperatrLt({
    tream,
    tak,
    reurce,
    peratrLt,
    ntlState = null,
    fallbackFntDct = null,
  }) {
    
    
    reurce = reurce || Dct.ety;
    ntlState = ntlState || new EvalState();
    f (!peratrLt) {
      thrw new Errr('getOperatrLt: mng "peratrLt" parameter');
    }
    cnt elf = th;
    cnt xref = th.xref;
    let parngText = fale;
    cnt lcalImageCache = new LcalImageCache();
    cnt lcalClrSpaceCache = new LcalClrSpaceCache();
    cnt lcalGStateCache = new LcalGStateCache();
    cnt lcalTlngPatternCache = new LcalTlngPatternCache();
    cnt lcalShadngPatternCache = new Map();
    cnt xbj = reurce.get("XObject") || Dct.ety;