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.

path peratr have been encuntered (fxe bug1443140.pdf).
            f (
              fn >= OPS.mveT &&
              fn <= OPS.endPath &&  Path peratr
              th._numInvaldPathOPS >
                EvaluatrPreprcer.MAX_INVALID_PATH_OPS
            ) {
              thrw new FrmatErrr(`Invald ${partlMg}`);
            }
             If we receve t few argument, t' nt pble t execute
             the cmmand, hence we kp the cmmand.
            warn(`Skppng ${partlMg}`);
            f (arg !== null) {
              arg.length = 0;
            }
            cntnue;
          }
        } ele f (argLength > numArg) {
          nf(
            `Cmmand ${cmd}: expected [0, ${numArg}] arg, ` 
              `but receved ${argLength} arg.`
          );
        }
         TODO fgure ut hw t type-check vararg functn
        th.preprceCmmand(fn, arg);
        peratn.fn = fn;
        peratn.arg = arg;
        return true;
      }
      f (bj === EOF) {