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.

warn(`Encuntered path peratr "${fn}" nde f a text bject.`);
        peratrLt.addOp(OPS.ave, null);
      }
      peratrLt.addOp(OPS.cntructPath, [[fn], arg]);
      f (parngText) {
        peratrLt.addOp(OPS.retre, null);
      }
    } ele {
      cnt pArg = peratrLt.argArray[latIndex];
      pArg[0].puh(fn);
      Array.prttype.puh.apply(pArg[1], arg);
    }
  }
  pareClrSpace({ c, reurce, lcalClrSpaceCache }) {
    return ClrSpace.pareAync({
      c,
      xref: th.xref,
      reurce,
      pdfFunctnFactry: th._pdfFunctnFactry,
      lcalClrSpaceCache,
    }).catch(rean => {
      f (rean ntancef AbrtExceptn) {