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)

).toEqual(["baz"]);
    });
  });
  describe("toRomanNumerals", function () {
    it("handles invalid arguments", function () {
      for (const input of ["foo", -1, 0]) {
        expect(function () {
          toRomanNumerals(input);
        }).toThrow(new Error("The number should be a positive integer."));
      }
    });
    it("converts numbers to uppercase Roman numerals", function () {
      expect(toRomanNumerals(1)).toEqual("I");
      expect(toRomanNumerals(6)).toEqual("VI");
      expect(toRomanNumerals(7)).toEqual("VII");
      expect(toRomanNumerals(8)).toEqual("VIII");
      expect(toRomanNumerals(10)).toEqual("X");
      expect(toRomanNumerals(40)).toEqual("XL");
      expect(toRomanNumerals(100)).toEqual("C");
      expect(toRomanNumerals(500)).toEqual("D");
      expect(toRomanNumerals(1000)).toEqual("M");
      expect(toRomanNumerals(2019)).toEqual("MMXIX");
    });
    it("converts numbers to lowercase Roman numerals", function () {
      expect(toRomanNumerals(1,  true)).toEqual("i");
      expect(toRomanNumerals(6,  true)).toEqual("vi");
      expect(toRomanNumerals(7,  true)).toEqual("vii");
      expect(toRomanNumerals(8,  true)).toEqual("viii");
      expect(toRomanNumerals(10,  true)).toEqual("x");
      expect(toRomanNumerals(40,  true)).toEqual("xl");