A snap roll is stall maneuver. It is not the same as a tip stall. The best way to prevent a snap is to not stall the wing. Reducing elevator throw will help. From straight and level flight, pull into a loop with full deflection on the stick. If the plane doesn't snap at the top of the loop add throw until it does. Not reduce the throws slightly until it can complete a full deflection loop without snapping. This should help with any inadvertent snaps.