Break out of thread if shard_iterator is nil
Break out of thread if shard_iterator is nil

- In the process of a shard split or merge, data will still be added to the stream. Once Kinesis is ready to process data again, it was maintain the order that the data was added so it will process the remaining events added to the “parent” shard. Once all the data has been read, it will return a “NULL” shard iterator which will blow up if we don’t exit the thread/handle the exception. 
ello/kinesis-stream-reader