I've always played that you can play a spell even if it has no actual effect, for the purposes of gaining the Elder Wand bonus.
A similar case would be to play Lumos when the Basilisk is in play - nothing explicitly stops you playing the spell, it just has no actual effect.
This was my thinking. However, there is a subtle difference. With Lumos, you have a valid target: a card you are trying to draw. You are just prevented from finishing the card instructions.
Here, no valid target even exists.
That said, the concept of "target" died get exist in this game, so I dint think urban matters. (It's just a remnant in mind from other games like Magic: The Gathering.)