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)

this.modificationDate = isString(modificationDate)
      ? modificationDate
      : null;
  }
  /**
   * Set the flags.
   *
   * @public
   * @memberof Annotation
   * @param {number} flags - Unsigned 32-bit integer specifying annotation
   *                         characteristics
   * @see {@link shared/util.js}
   */
  setFlags(flags) {
    this.flags = Number.isInteger(flags) && flags > 0 ? flags : 0;
  }
  /**
   * Check if a provided flag is set.
   *
   * @public
   * @memberof Annotation
   * @param {number} flag - Hexadecimal representation for an annotation
   *                        characteristic
   * @returns {boolean}
   * @see {@link shared/util.js}
   */
  hasFlag(flag) {