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.
result = self.lambda_client.invoke(
            FunctionName=TEST_LAMBDA_NAME_ENV, Payload=b'{}')
        result_data = result['Payload']
        self.assertEqual(result['StatusCode'], 200)
        self.assertDictEqual(json.load(result_data), vars)
        
        result = self.lambda_client.get_function_configuration(
            FunctionName=TEST_LAMBDA_NAME_ENV)
        self.assertEqual(result['Environment'], {'Variables': vars})
        
        testutil.delete_lambda_function(TEST_LAMBDA_NAME_ENV)
    def test_invocation_with_qualifier(self):
        lambda_name = 'test_lambda_%s' % short_uid()
        bucket_name = 'test-bucket-lambda2'
        bucket_key = 'test_lambda.zip'
        
        zip_file = testutil.create_lambda_archive(
            load_file(TEST_LAMBDA_PYTHON),
            get_content=True,
            libs=TEST_LAMBDA_LIBS,
            runtime=LAMBDA_RUNTIME_PYTHON27
        )
        self.s3_client.create_bucket(Bucket=bucket_name)
        self.s3_client.upload_fileobj(
            BytesIO(zip_file), bucket_name, bucket_key)
        
        response = self.lambda_client.create_function(
            FunctionName=lambda_name, Handler='handler.handler',
            Runtime=lambda_api.LAMBDA_RUNTIME_PYTHON27, Role='r1',