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.
executor.cleanup()
        status = executor.get_docker_container_status(func_arn)
        self.assertEqual(status, 0)
        self.assertEqual(len(executor.get_all_container_names()), 0)
        
        testutil.delete_lambda_function(func_name)
    def test_docker_command_for_separate_container_lambda_executor(self):
        
        if not isinstance(lambda_api.LAMBDA_EXECUTOR,
                          lambda_executors.LambdaExecutorSeparateContainers):
            return
        executor = lambda_api.LAMBDA_EXECUTOR
        func_name = 'test_docker_command_for_separate_container_lambda_executor'
        func_arn = lambda_api.func_arn(func_name)
        handler = 'handler'
        lambda_cwd = '/app/lambda'
        network = 'compose_network'
        config.LAMBDA_DOCKER_NETWORK = network
        cmd = executor.prepare_execution(func_arn, {}, LAMBDA_RUNTIME_NODEJS810, '', handler, lambda_cwd)
        expected = 'docker run -v "%s":/var/task   --network="%s"  --rm "lambci/lambda:%s" "%s"' % (
            lambda_cwd, network, LAMBDA_RUNTIME_NODEJS810, handler)
        self.assertIn(('--network="%s"' % network), cmd, 'cmd=%s expected=%s' % (cmd, expected))
        config.LAMBDA_DOCKER_NETWORK = ''
    def test_destroy_idle_containers(self):
        
        if not isinstance(lambda_api.LAMBDA_EXECUTOR,
                          lambda_executors.LambdaExecutorReuseContainers):
            return
        executor = lambda_api.LAMBDA_EXECUTOR
        func_name = 'test_destroy_idle_containers'