PDF.js version: 3.5.141

These two properties should be marked as not mandatory as they are initialized if not present
if (!this.pdfDocument) {
      return;
    }
    let newScale = this._currentScale;
    if (scaleFactor > 1) {
      newScale = Math.round(newScale * scaleFactor * 100) / 100;
    } else {
      steps ??= 1;
      do {
        newScale =
          Math.ceil((newScale * DEFAULT_SCALE_DELTA).toFixed(2) * 10) / 10;
      } while (--steps > 0 && newScale < MAX_SCALE);
    }
    this.#setScale(Math.min(MAX_SCALE, newScale), {
      noScroll: false,
      drawingDelay,
    });
  }
  /**
   * Decrease the current zoom level one, or more, times.
   * @param {ChangeScaleOptions} [options]
   */
  decreaseScale({ drawingDelay, scaleFactor, steps } = {}) {