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.

} else {
      fileType = "OpenType";
    }
  } else if (isType1File(file)) {
    if (composite) {
      fileType = "CIDFontType0";
    } else {
      fileType = type === "MMType1" ? "MMType1" : "Type1";
    }
  } else if (isCFFFile(file)) {
    if (composite) {
      fileType = "CIDFontType0";
      fileSubtype = "CIDFontType0C";
    } else {
      fileType = type === "MMType1" ? "MMType1" : "Type1";
      fileSubtype = "Type1C";
    }
  } else {
    warn("getFontFileType: Unable to detect correct font file Type/Subtype.");
    fileType = type;
    fileSubtype = subtype;
  }
  return [fileType, fileSubtype];
}
function applyStandardFontGlyphMap(map, glyphMap) {
  for (const charCode in glyphMap) {
    map[+charCode] = glyphMap[charCode];
  }
}
function buildToFontChar(encoding, glyphsUnicodeMap, differences) {