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)

/**
   * Create an `Annotation` object of the correct type for the given reference
   * to an annotation dictionary. This yields a promise that is resolved when
   * the `Annotation` object is constructed.
   *
   * @param {XRef} xref
   * @param {Object} ref
   * @param {PDFManager} pdfManager
   * @param {Object} idFactory
   * @returns {Promise} A promise that is resolved with an {Annotation}
   *   instance.
   */
  static create(xref, ref, pdfManager, idFactory) {
    return pdfManager.ensureCatalog("acroForm").then(acroForm => {
      return pdfManager.ensure(this, "_create", [
        xref,
        ref,
        pdfManager,
        idFactory,
        acroForm,
      ]);
    });
  }
  /**
   * @private
   */
  static _create(xref, ref, pdfManager, idFactory, acroForm) {