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.
def __init__(self, id, env=None):
        self.id = id
        self.env = env
        self.created_at = None
    def name(self):
        return self.id
    def __repr__(self):
        return self.__str__()
    def __str__(self):
        return '<%s:%s>' % (self.__class__.__name__, self.id)
class KinesisStream(Component):
    def __init__(self, id, params=None, num_shards=1, connection=None):
        super(KinesisStream, self).__init__(id)
        params = params or {}
        self.shards = []
        self.stream_name = params.get('name', self.name())
        self.num_shards = params.get('shards', num_shards)
        self.conn = connection
        self.stream_info = params
    def name(self):
        return self.id.split(':stream/')[-1]
    def connect(self, connection):
        self.conn = connection
    def describe(self):
        r = self.conn.describe_stream(StreamName=self.stream_name)
        return r.get('StreamDescription')
    def create(self, raise_on_error=False):