Any tips on how to implement a "decrement" badge option? #4431

I would like to do a PR to allow for a "decrement" badge option in push controller.
Adding a

if (typeof badge == 'string' && badge.toLowerCase() === 'decrement') {
  restUpdate = { badge: { __op: 'Increment', amount: -1 } }
}

is easy, by I guess we should take care of zero values, to avoid negative badge value.
Do you have any idea how I could implement this?
Or what would be the best way to have a decrement option in push controller?
(It would great to cancel a notification like an invite for example)

Thanks