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.
---
        operationId: 'invokeFunction'
        parameters:
            - name: 'request'
              in: body
    """
    
    arn = func_arn(function)
    
    m = re.match('(arn:aws:lambda:.*:.*:function:[a-zA-Z0-9-_]+)(:.*)?', arn)
    if m and m.group(2):
        qualifier = m.group(2)[1:]
        arn = m.group(1)
    else:
        qualifier = request.args.get('Qualifier')
    data = request.get_data()
    if data:
        data = to_str(data)
        try:
            data = json.loads(data)
        except Exception:
            try:
                
                data = json.loads(parse_chunked_data(data))
            except Exception:
                return error_response('The payload is not JSON: %s' % data, 415,
                                      error_type='UnsupportedMediaTypeException')
    
    invocation_type = request.environ.get('HTTP_X_AMZ_INVOCATION_TYPE', 'RequestResponse')
    def _create_response(result, status_code=200):