The problem does not exists.

Maybe I've worded wrong before, but stop casting a skill require zero effort and frankly I don't see the need to program the game to see a miss when you click on ress skill.

The real issue OP maybe wants address, is have three healers burning their swiftcast for a ress, and two of them being wasted.

Well, there are no means to avoid it: healers can cast swiftcast for any reason and it cannot be blocked just because someone died. I really don't care to have a miss on res because someone is ressing, but my swiftcast gone and done.