PDF.js version: 3.5.141

These two properties should be marked as not mandatory as they are initialized if not present
return this._pageLabels?.[this._currentPageNumber - 1] ?? null;
  }
  /**
   * @param {string} val - The page label.
   */
  set currentPageLabel(val) {
    if (!this.pdfDocument) {
      return;
    }
    let page = val | 0; 
    if (this._pageLabels) {
      const i = this._pageLabels.indexOf(val);
      if (i >= 0) {
        page = i + 1;
      }
    }
    
    if (!this._setCurrentPageNumber(page,  true)) {
      console.error(`currentPageLabel: "${val}" is not a valid page.`);
    }
  }
  /**
   * @type {number}
   */
  get currentScale() {