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>}`)
const params = this._params;
    return shadow(this, "loadingParams", {
      disableAutoFetch: params.disableAutoFetch,
      disableFontFace: params.disableFontFace,
    });
  }
}
/**
 * A PDF document and page is built of many objects. E.g. there are objects for
 * fonts, images, rendering code, etc. These objects may get processed inside of
 * a worker. This class implements some basic methods to manage these objects.
 * @ignore
 */
class PDFObjects {