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.
policies = iam_client.list_policies(Scope='Local', MaxItems=500)['Policies']
        matching = [p for p in policies if p['PolicyName'] == 'lambda_policy_%s' % TEST_LAMBDA_NAME_PY]
        self.assertEqual(len(matching), 1)
        self.assertIn(':policy/', matching[0]['Arn'])
        
        resp = lambda_client.remove_permission(FunctionName=TEST_LAMBDA_NAME_PY,
            StatementId=resp['Statement'], Qualifier='qual1', RevisionId='r1')
        self.assertEqual(resp['ResponseMetadata']['HTTPStatusCode'], 200)
class TestPythonRuntimes(LambdaTestBase):
    @classmethod
    def setUpClass(cls):
        cls.lambda_client = aws_stack.connect_to_service('lambda')
        cls.s3_client = aws_stack.connect_to_service('s3')
        zip_file = testutil.create_lambda_archive(
            load_file(TEST_LAMBDA_PYTHON),
            get_content=True,
            libs=TEST_LAMBDA_LIBS,
            runtime=LAMBDA_RUNTIME_PYTHON27
        )
        testutil.create_lambda_function(
            func_name=TEST_LAMBDA_NAME_PY,
            zip_file=zip_file,
            runtime=LAMBDA_RUNTIME_PYTHON27
        )
    @classmethod
    def tearDownClass(cls):
        testutil.delete_lambda_function(TEST_LAMBDA_NAME_PY)
    def test_invocation_type_not_set(self):
        result = self.lambda_client.invoke(