PDF.js version: 3.5.141

These two properties should be marked as not mandatory as they are initialized if not present
return this._currentScale !== UNKNOWN_SCALE
      ? this._currentScale
      : DEFAULT_SCALE;
  }
  /**
   * @param {number} val - Scale of the pages in percents.
   */
  set currentScale(val) {
    if (isNaN(val)) {
      throw new Error("Invalid numeric scale.");
    }
    if (!this.pdfDocument) {
      return;
    }
    this.#setScale(val, { noScroll: false });
  }
  /**
   * @type {string}
   */
  get currentScaleValue() {
    return this._currentScaleValue;
  }
  /**
   * @param val - The scale of the pages (in percent or predefined value).
   */
  set currentScaleValue(val) {