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.
Code={
                'S3Bucket': bucket_name,
                'S3Key': bucket_key
            },
            Publish=True
        )
        self.assertIn('Version', response)
        
        data_before = b'{"foo": "bar with \'quotes\\""}'
        result = self.lambda_client.invoke(
            FunctionName=lambda_name,
            Payload=data_before,
            Qualifier=response['Version']
        )
        data_after = json.loads(result['Payload'].read())
        self.assertEqual(json.loads(to_str(data_before)), data_after['event'])
        context = data_after['context']
        self.assertEqual(response['Version'], context['function_version'])
        self.assertEqual(lambda_name, context['function_name'])
        
        expected = ['Lambda log message - print function']
        if use_docker():
            
            
            expected.append('.*Lambda log message - logging module')
        self.check_lambda_logs(lambda_name, expected_lines=expected)
        
        testutil.delete_lambda_function(lambda_name)
    def test_upload_lambda_from_s3(self):
        lambda_name = 'test_lambda_%s' % short_uid()