When uploading a pdf file, I get Warning: Unimplemented widget field type "null", falling back to base field type at pdf.worker.js. The file is not loading.
I'm using the chrome browser. All other files are processed fine, but this one is not. Help solve the problem.
[usn2020.pdf](https://github.com/mozilla/pdf.js/files/5936611/usn2020.pdf)

return ch === 0x20 || ch === 0x09 || ch === 0x0d || ch === 0x0a;
}
/**
 * AcroForm field names use an array like notation to refer to
 * repeated XFA elements e.g. foo.bar[nnn].
 * see: XFA Spec Chapter 3 - Repeated Elements
 *
 * @param {string} path - XFA path name.
 * @returns {Array} - Array of Objects with the name and pos of
 * each part of the path.
 */
function parseXFAPath(path) {
  const positionPattern = /(.+)\[([0-9]+)\]$/;
  return path.split(".").map(component => {
    const m = component.match(positionPattern);
    if (m) {
      return { name: m[1], pos: parseInt(m[2], 10) };
    }
    return { name: component, pos: 0 };
  });
}
function escapePDFName(str) {
  const buffer = [];
  let start = 0;
  for (let i = 0, ii = str.length; i < ii; i++) {
    const char = str.charCodeAt(i);
    
    if (