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.
return send_dynamodb_request('', 'UpdateTimeToLive', json.dumps({
        'TableName': table_name,
        'TimeToLiveSpecification': {
            'AttributeName': 'ExpireItem',
            'Enabled': ttl_status
        }
    }))
def send_dynamodb_request(path, action, request_body):
    headers = {
        'Host': 'dynamodb.amazonaws.com',
        'x-amz-target': 'DynamoDB_20120810.{}'.format(action),
        'authorization': 'some_token'
    }
    url = '{}/{}'.format(os.getenv('TEST_DYNAMODB_URL'), path)
    return requests.put(url, data=request_body, headers=headers, verify=False)
def create_sqs_queue(queue_name):
    """Utility method to create a new queue via SQS API"""
    client = aws_stack.connect_to_service('sqs')
    
    queue_url = client.create_queue(QueueName=queue_name)['QueueUrl']
    
    queue_arn = client.get_queue_attributes(
        QueueUrl=queue_url,
        AttributeNames=['QueueArn'],
    )['Attributes']['QueueArn']
    return {
        'QueueUrl': queue_url,
        'QueueArn': queue_arn,
    }