wrong release function in async example

  release(item) {
    const index = this.items.indexOf(item);
    if (index < 0) throw new Error('Pool: release unexpected item');
    if (this.free[index]) throw new Error('Pool: release not captured');
    this.free[index] = true;
    this.available++;
    if (this.queue.length > 0) {
      const { resolve, timer } = this.queue.shift();
      clearTimeout(timer);
      if (resolve) setTimeout(resolve, 0, item);
    }
  }

error - we should not free released item if we resolve it for user in queue

  release(item) {
    const index = this.items.indexOf(item);
    if (index < 0) throw new Error('Pool: release unexpected item');
    if (this.free[index]) throw new Error('Pool: release not captured');
    if (this.queue.length > 0) {
      const { resolve, timer } = this.queue.shift();
      clearTimeout(timer);
      if (resolve) setTimeout(resolve, 0, item);
    } else { 
      this.free[index] = true;
      this.available++;
    }
  }

Find the async example containing the release(item) function and inspect how queued requests receive released items. Verify the queue handoff and free/available accounting, then exercise the example's release behavior to confirm that an item handed directly to a queued user is not also counted as free.