ThreadPoolExecutor(1, 1, 0, TimeUnit.SECONDS, SynchronousQueue()) {
    private val exceptions: BlockingQueue<Exception> = LinkedBlockingQueue()

    override fun execute(runnable: Runnable) {
      super.execute {
        try {
          runnable.run()
        } catch (e: Exception) {
          exceptions.add(e)
        }
      }
    }

    fun takeException(): Exception {