PDF files:
[1.pdf](https://github.com/mozilla/pdf.js/files/2955999/1.pdf)
[2.pdf](https://github.com/mozilla/pdf.js/files/2956000/2.pdf)
[3.pdf](https://github.com/mozilla/pdf.js/files/2956002/3.pdf)

Configuration:
- Web browser and its version: Chrome, Firefox
- Operating system and its version: Ubuntu, macOS
- PDF.js version: 2.2.42, but the same was with 2.1.x, and with https://mozilla.github.io/pdf.js/web/viewer.html
- Is a browser extension: no

Steps to reproduce the problem:
1. Select text
2. Copy text

What went wrong?

Getting this:
`OpenSansisahumanistsansseriftypefacedesignedbySteveMatteson.OpenSanswasdesignedwithanuprightstress,openformsandaneu-tral,yetfriendlyappearance.Itwasoptimizedforprint,web,andmobileinterfaces,andhasexcellentlegibilitycharacteristicsinitsletterforms(seefigureonthefollowingpage).ThisfontisavailablefromtheGoogleFontDirectory[]asTrueTypefileslicensedundertheApacheLicenseversion..`

Instead of this:
`Open Sans is a humanist sans serif typeface designed by Steve Matteson.
Open Sans was designed with an upright stress, open forms and a neutral,
yet friendly appearance. It was optimized for print, web, and mobile
interfaces, and has excellent legibility characteristics in its letterforms (see
figure 1 on the following page). This font is available from the Google Font
Directory [1] as TrueType files licensed under the Apache License version 2.0.`

This is quite significant problem, because I would say 1/20 of scientific papers encounter this problem.

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) {