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.
def do_execute(*args):
            
            invocation_time = int(time.time() * 1000)
            
            try:
                result, log_output = self._execute(func_arn, func_details, event, context, version)
            finally:
                self.function_invoke_times[func_arn] = invocation_time
            
            self._store_logs(func_details, log_output, invocation_time)
            
            return result, log_output
        
        if asynchronous:
            LOG.debug('Lambda executed in Event (asynchronous) mode, no response from this '
                      'function will be returned to caller')
            FuncThread(do_execute).start()
            return None, 'Lambda executed asynchronously.'
        return do_execute()
    def _execute(self, func_arn, func_details, event, context=None, version=None):
        """ This method must be overwritten by subclasses. """
        raise Exception('Not implemented.')
    def startup(self):
        pass
    def cleanup(self, arn=None):
        pass
    def _store_logs(self, func_details, log_output, invocation_time):
        if not aws_stack.is_service_enabled('logs'):