3.0.4 crashing if empty response to a message


With Get Response from server checked, I’m unclear what the correct response is if there is no message to send back. On 2.8.3 we could send

{‘payload’: {‘success’: ‘true’}}

but on 3.0.4 this crashes SMSSync

We’ve tried adding the ‘error’: null line from the docs at http://smssync.ushahidi.com/developers/ but it still crashes …

Has anyone found a way to respond that there is nothing to send out on 3.0.4 ?