Icicle\Observable\Internal\EmitQueue::isFailed PHP Method

    public function isFailed() : bool
    {
        return $this->failed;
    }

 /**
  * {@inheritdoc}
  */
 public function getReturn()
 {
     if (null === $this->placeholder || null !== $this->awaitable) {
         throw new UninitializedError('wait() must be called before calling this method.');
     }
     if (!$this->complete) {
         throw new IncompleteError('The observable has not completed.');
     }
     if ($this->queue->isFailed()) {
         throw $this->current;
     }
     return $this->current;
 }