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._structTreePromise ||= this._transport.getStructTree(
      this._pageIndex
    ));
  }
  /**
   * Destroys the page object.
   * @private
   */
  _destroy() {
    this.destroyed = true;
    this._transport.pageCache[this._pageIndex] = null;
    const waitOn = [];
    for (const [intent, intentState] of this._intentStates) {
      this._abortOperatorList({
        intentState,
        reason: new Error("Page was destroyed."),
        force: true,
      });
      if (intent === "oplist") {
        
        continue;