May be a duplicate of https://github.com/localstack/localstack/issues/988 but due to the age I will re raise.

I'm having issues when I throw an exception in a lambda - it isn't appearing on my dead letter queue. Is there something I am missing, I would like an sqs event exception to appear on the poison queue when an exception happens.

Below is the basic config:
 ````
    sqsclient.create_queue(QueueName = 'test-queue')
    sqsclient.create_queue(QueueName = 'test-queue-poison')

    lambda_client.create_function(
            FunctionName='MyFunction',
            Runtime='dotnetcore2.1',
            Role='role',
            Handler='Handler',
            Code=code,
	    DeadLetterConfig={'TargetArn': 'test-queue-poison-arn'})

     lambda_client.create_event_source_mapping(
		EventSourceArn='test-queue-arn',
		FunctionName='MyFunction',
		Enabled=True,
		BatchSize=100,
		StartingPosition='LATEST')
````

So when I raise a new (.net)exception within the lambda function no message is going to the dead letter queue. I can confirm that all is attached together OK as all other scenarios work, and the above code is pseudo-ish.
GET_STATUS_SLEEP_SECS = 5
        GET_STATUS_RETRIES = 50
        for i in range(0, GET_STATUS_RETRIES):
            try:
                status = self.get_status()
                if status == 'ACTIVE':
                    return
            except Exception:
                
                pass
            time.sleep(GET_STATUS_SLEEP_SECS)
        raise Exception('Failed to get active status for stream "%s", giving up' % self.stream_name)
    def destroy(self):
        self.conn.delete_stream(StreamName=self.stream_name)
        time.sleep(2)
class KinesisShard(Component):
    MAX_KEY = '340282366920938463463374607431768211455'
    def __init__(self, id):
        super(KinesisShard, self).__init__(id)
        self.stream = None
        self.start_key = '0'
        self.end_key = KinesisShard.MAX_KEY  
        self.child_shards = []
    def print_tree(self, indent=''):
        print('%s%s' % (indent, self))
        for c in self.child_shards:
            c.print_tree(indent=indent + '   ')
    def length(self):