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.
zip_file_content = load_file(tmp_file, mode='rb')
    
    lambda_handler = generic_handler
    if runtime == LAMBDA_RUNTIME_JAVA8:
        
        
        
        lambda_handler, zip_file_content = get_java_handler(zip_file_content, handler_name, tmp_file)
    if not is_local_mount:
        
        if not is_zip_file(zip_file_content):
            raise ClientError(
                'Uploaded Lambda code for runtime ({}) is not in Zip format'.format(runtime))
        unzip(tmp_file, lambda_cwd)
    
    if runtime != LAMBDA_RUNTIME_JAVA8:
        handler_file = get_handler_file_from_name(handler_name, runtime=runtime)
        handler_function = get_handler_function_from_name(handler_name, runtime=runtime)
        main_file = '%s/%s' % (lambda_cwd, handler_file)
        if not os.path.exists(main_file):
            
            
            
            if not is_local_mount or not use_docker() or config.LAMBDA_REMOTE_DOCKER:
                file_list = run('cd "%s"; du -d 3 .' % lambda_cwd)
                config_debug = ('Config for local mount, docker, remote: "%s", "%s", "%s"' %
                    (is_local_mount, use_docker(), config.LAMBDA_REMOTE_DOCKER))
                LOG.debug('Lambda archive content:\n%s' % file_list)
                raise ClientError(error_response(
                    'Unable to find handler script (%s) in Lambda archive. %s' % (main_file, config_debug),