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.
zip_file=zip_file,
            runtime=LAMBDA_RUNTIME_PYTHON27,
            envvars={'Hello': 'World'}
        )
        self.assertEqual(len(executor.get_all_container_names()), 0)
        self.assertDictEqual(executor.function_invoke_times, {})
        
        durations = []
        num_iterations = 3
        for i in range(0, num_iterations + 1):
            prev_invoke_time = None
            if i > 0:
                prev_invoke_time = executor.function_invoke_times[func_arn]
            start_time = time.time()
            self.lambda_client.invoke(FunctionName=func_name, Payload=b'{}')
            duration = time.time() - start_time
            self.assertEqual(len(executor.get_all_container_names()), 1)
            
            if i > 0:
                self.assertGreater(executor.function_invoke_times[func_arn], prev_invoke_time)
            else:
                self.assertGreater(executor.function_invoke_times[func_arn], 0)
            durations.append(duration)
        
        for i in range(1, num_iterations + 1):
            self.assertLess(durations[i], durations[0])
        status = executor.get_docker_container_status(func_arn)
        self.assertEqual(status, 1)
        container_network = executor.get_docker_container_network(func_arn)
        self.assertEqual(container_network, 'default')