GrumPHP\Exception\RuntimeException::invalidTaskReturnType PHP Метод

    public static function invalidTaskReturnType(TaskInterface $task)
    {
        return new self(sprintf('The %s task did not return a TaskResult.', $task->getName()));
    }

 /**
  * @param TaskInterface    $task
  * @param ContextInterface $context
  *
  * @return TaskResultInterface
  * @throws RuntimeException
  */
 private function runTask(TaskInterface $task, ContextInterface $context)
 {
     try {
         $this->eventDispatcher->dispatch(TaskEvents::TASK_RUN, new TaskEvent($task, $context));
         $result = $task->run($context);
     } catch (RuntimeException $e) {
         $result = TaskResult::createFailed($task, $context, $e->getMessage());
     }
     if (!$result instanceof TaskResultInterface) {
         throw RuntimeException::invalidTaskReturnType($task);
     }
     if (!$result->isPassed() && !$this->grumPHP->isBlockingTask($task->getName())) {
         $result = TaskResult::createNonBlockingFailed($result->getTask(), $result->getContext(), $result->getMessage());
     }
     if (!$result->isPassed()) {
         $e = new RuntimeException($result->getMessage());
         $this->eventDispatcher->dispatch(TaskEvents::TASK_FAILED, new TaskFailedEvent($task, $context, $e));
         return $result;
     }
     $this->eventDispatcher->dispatch(TaskEvents::TASK_COMPLETE, new TaskEvent($task, $context));
     return $result;
 }