Hi Judge! For a spell on the stack, if its targets all become invalid does it stay until it moves to resolve? I didn't see a state based action that cleaned them up but could have missed something. Such as if my removal spell is blanked by the target being sacrificed but I have on-stack interaction (a redirect, Nivmagus Elemental, Spell Queller, etc at my own spell). Thanks!
Spells only leave the stack when they go to resolve or when a spell or ability moves them from the stack, such as a counterspell effect.
A spell that was cast with legal targets but whose targets all become illegal stays on the stack until it goes to resolve, at which point it will fail to resolve and be removed from the stack.
What all this means is that you can feed a spell that has lost its targets to your Spell Queller or Niv-Magus Elemental without having to worry about state-based actions taking it away from you.
