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.

if (
    typeof PDFJSDev === "undefined" ||
    PDFJSDev.test("!PRODUCTION || TESTING")
  ) {
    assert(
      typeof value === "number" && !Number.isNaN(value),
      `safeString16: Unexpected input "${value}".`
    );
  }
  
  if (value > 0x7fff) {
    value = 0x7fff;
  } else if (value < -0x8000) {
    value = -0x8000;
  }
  return String.fromCharCode((value >> 8) & 0xff, value & 0xff);
}
function isTrueTypeFile(file) {
  const header = file.peekBytes(4);
  return (
    readUint32(header, 0) === 0x00010000 || bytesToString(header) === "true"
  );
}
function isTrueTypeCollectionFile(file) {