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.
func_arn = lambda_api.func_arn(func_name)
        
        executor.destroy_existing_docker_containers()
        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,
            zip_file=zip_file,
            runtime=LAMBDA_RUNTIME_PYTHON27,
            envvars={'Hello': 'World'}
        )
        self.assertEqual(len(executor.get_all_container_names()), 0)
        self.lambda_client.invoke(FunctionName=func_name, Payload=b'{}')
        self.assertEqual(len(executor.get_all_container_names()), 1)
        
        executor.idle_container_destroyer()
        self.assertEqual(len(executor.get_all_container_names()), 1)
        
        executor.function_invoke_times[func_arn] = time.time() - lambda_executors.MAX_CONTAINER_IDLE_TIME_MS
        executor.idle_container_destroyer()
        self.assertEqual(len(executor.get_all_container_names()), 0)
        
        testutil.delete_lambda_function(func_name)