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.
testutil.delete_lambda_function(lambda_name)
    def test_python_lambda_running_in_docker(self):
        if not use_docker():
            return
        zip_file = testutil.create_lambda_archive(
            load_file(TEST_LAMBDA_PYTHON3),
            get_content=True,
            libs=TEST_LAMBDA_LIBS,
            runtime=LAMBDA_RUNTIME_PYTHON36
        )
        testutil.create_lambda_function(
            func_name=TEST_LAMBDA_NAME_PY3,
            zip_file=zip_file,
            runtime=LAMBDA_RUNTIME_PYTHON36
        )
        result = self.lambda_client.invoke(
            FunctionName=TEST_LAMBDA_NAME_PY3, Payload=b'{}')
        result_data = result['Payload'].read()
        self.assertEqual(result['StatusCode'], 200)
        self.assertEqual(to_str(result_data).strip(), '{}')
        
        testutil.delete_lambda_function(TEST_LAMBDA_NAME_PY3)
    def test_handler_in_submodule(self):
        func_name = 'lambda-%s' % short_uid()
        zip_file = testutil.create_lambda_archive(
            load_file(TEST_LAMBDA_PYTHON), get_content=True,
            libs=TEST_LAMBDA_LIBS, runtime=LAMBDA_RUNTIME_PYTHON36,
            file_name='abc/def/main.py')
        testutil.create_lambda_function(func_name=func_name, zip_file=zip_file,