https://github.com/mozilla/pdf.js/blob/0df1a5661958df0c4ed2f73b0f3266d825c5c280/src/display/api.js#L710-L719
The return type signature `@returns {Promise<{num: number, gen: number}>}` is mismatched with its definition. (should be `@returns {Promise<number>}`)
return this._pageInfo.view;
  }
  /**
   * @param {GetViewportParameters} params - Viewport parameters.
   * @returns {PageViewport} Contains 'width' and 'height' properties
   *   along with transforms required for rendering.
   */
  getViewport({
    scale,
    rotation = this.rotate,
    offsetX = 0,
    offsetY = 0,
    dontFlip = false,
  } = {}) {
    return new PageViewport({
      viewBox: this.view,
      scale,
      rotation,
      offsetX,
      offsetY,
      dontFlip,
    });
  }
  /**
   * @param {GetAnnotationsParameters} params - Annotation parameters.
   * @returns {Promise<Array<any>>} A promise that is resolved with an
   *   {Array} of the annotation objects.
   */
  getAnnotations({ intent = null } = {}) {