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.
result_data = result['Payload'].read()
        self.assertEqual(result['StatusCode'], 200)
        self.assertDictEqual(
            json.loads(to_str(result_data)),
            {'validated': True, 'bucket': 'test_bucket', 'key': 'test_key'}
        )
class TestDockerBehaviour(LambdaTestBase):
    @classmethod
    def setUpClass(cls):
        cls.lambda_client = aws_stack.connect_to_service('lambda')
    def test_prime_and_destroy_containers(self):
        
        if not isinstance(lambda_api.LAMBDA_EXECUTOR,
                          lambda_executors.LambdaExecutorReuseContainers):
            return
        executor = lambda_api.LAMBDA_EXECUTOR
        func_name = 'test_prime_and_destroy_containers'
        func_arn = lambda_api.func_arn(func_name)
        
        executor.cleanup()
        self.assertEqual(len(executor.get_all_container_names()), 0)
        
        zip_file = testutil.create_lambda_archive(
            load_file(TEST_LAMBDA_ENV),
            get_content=True,
            libs=TEST_LAMBDA_LIBS,
            runtime=LAMBDA_RUNTIME_PYTHON27
        )
        testutil.create_lambda_function(
            func_name=func_name,