I'm sorry this happens. You can cope by having a few "evangelist" users you communicate with to balance the negativity. There's a bias for comment on code that's not perfect. When everything's perfect, no one has anything to say. Open source bring with it an open quorum.
Github in particular has no way of stopping drive-by comments and issues, right?
Disable Github issues and use a mailing list instead.
A mailing list doesn't stop drive-by comments and shenanigans. It just raises the barrier to entry.