set currentPageNumber(val) {
    if (!Number.isInteger(val)) {
      throw new Error("Invalid page number.");
    }
    if (!this.pdfDocument) {
      return;
    }
    // The intent can be to just reset a scroll position and/or scale.
    if (!this._setCurrentPageNumber(val, /* resetCurrentPageView = */ true)) {
      console.error(`currentPageNumber: "${val}" is not a valid page.`);
    }
  }
@param {number} val - The page number.