Volatile Parts damage question in SotM app

So I ran into this with the app and it seemed odd that it worked that way.   So Unity had Volatile Parts out which damages the non hero target with the lowest HP for two.   Ambuscade had a Sonic Mine in play, Unity had a Bee Bot in play, and Silver Gulch played Tyler Hayes.   I messed up on order and Hayes hit the Sonic Mine so I let it play out.   When Bee Bot was destroyed Volatile Parts triggered and damage was dealt to the Sonic Mine.   I would have expected Hayes to be the target since Sonic Mine was technically destroyed and wouldn't really have HP.  

So is the app correct in having Volatile Parts damage the Sonic Mine?

I don't think so. I think Christopher said that something can't be destroyed twice (let me see if I can find the link). However, it could have changed after Handelabra talked with Christopher about the app.

EDIT: Not sure if I read it wrong first, or you changed it, but the app is correct. While something is being destroyed, it is still a target, still ahs hp, and can still be targeted. Handelabra discussed with Christopher at length about how to handle "when destroyed" effects.

I updated the title and reworded one sentence to be a bit more clear.  Thanks for information.  

If a target has "when this card is destroyed" text then it remains a target until its destruction is complete.

That's unfortunate.   Makes Volatile Parts ineffective against a number of cards.  Thanks for confirming though.