Prevent sending batch requests with empty jobs

Hi,

As SQS only supports up to 10 message to batch push/batch delete, the queue automatically implements logic to splicing jobs by batch of 10. However, if you submitted an exact multiple of 10 (like 20 or 30), the last batch would have an empty array, which causes an exception on SQS.

This prevents batch requests to be sent if no job are sent.