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 false;
    }
    if (
      !(
        Number.isInteger(pageNumber) &&
        pageNumber > 0 &&
        pageNumber <= this.pagesCount
      )
    ) {
      console.error(`isPageCached: "${pageNumber}" is not a valid page.`);
      return false;
    }
    const pageView = this._pages[pageNumber - 1];
    return this.#buffer.has(pageView);
  }
  cleanup() {
    for (const pageView of this._pages) {
      if (pageView.renderingState !== RenderingStates.FINISHED) {
        pageView.reset();
      }
    }
  }
  /**
   * @private
   */
  _cancelRendering() {