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)

case "Tx":
            return new TextWidgetAnnotation(parameters);
          case "Btn":
            return new ButtonWidgetAnnotation(parameters);
          case "Ch":
            return new ChoiceWidgetAnnotation(parameters);
        }
        warn(
          'Unimplemented widget field type "' +
            fieldType +
            '", ' +
            "falling back to base field type."
        );
        return new WidgetAnnotation(parameters);
      case "Popup":
        return new PopupAnnotation(parameters);
      case "FreeText":
        return new FreeTextAnnotation(parameters);
      case "Line":
        return new LineAnnotation(parameters);
      case "Square":
        return new SquareAnnotation(parameters);
      case "Circle":
        return new CircleAnnotation(parameters);
      case "PolyLine":
        return new PolylineAnnotation(parameters);
      case "Polygon":
        return new PolygonAnnotation(parameters);
      case "Caret":
        return new CaretAnnotation(parameters);