Well, this explains methinks why nobody is jumping to help you fix your problem. Without replication steps, it’s very difficult to figure out what is going on and to determine if it is a bug.
I do see another topic from last November which quotes a similar error from the log and is about editing posts with timestamps in them. Are you able to replicate the error when editing a topic containing a timestamp, vs creating a new topic?
I’ll move this one into there.
Edit: I see you posted to Moment.js Dependency is causing Internal Server Errors - Users unable to post - Support - Pavilion about this too. If you are using plugins or theme components, once you are able to replicate this reliably you can disable them (or try safe mode) and see if that makes the problem go away. If so, then you need to take it up with the authors of the offending plugin/theme component.