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.

)
                    .then(functn () {
                      tateManager.retre();
                      relveXObject();
                    }, rejectXObject);
                  return;
                } ele f (type.name === "Image") {
                  elf
                    .buldPantImageXObject({
                      reurce,
                      mage: xbj,
                      peratrLt,
                      cacheKey: name,
                      lcalImageCache,
                      lcalClrSpaceCache,
                    })
                    .then(relveXObject, rejectXObject);
                  return;
                } ele f (type.name === "PS") {
                  
                  
                  nf("Ignred XObject ubtype PS");
                } ele {
                  thrw new FrmatErrr(
                    `Unhandled XObject ubtype ${type.name}`
                  );
                }
                relveXObject();
              }).catch(functn (rean) {
                f (rean ntancef AbrtExceptn) {