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.
os.chdir(lambda_cwd)
            if environment:
                os.environ.update(environment)
            result = lambda_function(event, context)
            queue.put(result)
        process = Process(target=do_execute)
        with CaptureOutput() as c:
            process.run()
        result = queue.get()
        
        log_output = ''
        for stream in (c.stdout(), c.stderr()):
            if stream:
                log_output += ('\n' if log_output else '') + stream
        return result, log_output
    def execute_java_lambda(self, event, context, handler, main_file):
        event_file = EVENT_FILE_PATTERN.replace('*', short_uid())
        save_file(event_file, json.dumps(event))
        TMP_FILES.append(event_file)
        class_name = handler.split('::')[0]
        classpath = '%s:%s:%s' % (LAMBDA_EXECUTOR_JAR, main_file, Util.get_java_classpath(main_file))
        cmd = 'java -cp %s %s %s %s' % (classpath, LAMBDA_EXECUTOR_CLASS, class_name, event_file)
        result, log_output = self.run_lambda_executor(cmd)
        LOG.debug('Lambda result / log output:\n%s\n> %s' % (
            result.strip(), log_output.strip().replace('\n', '\n> ')))
        return result, log_output
class Util:
    debug_java_port = False
    @classmethod
    def get_java_opts(cls):