Kalista canceling Tresh lantern

Played Kalista with Tresh sup. During a fight botlane i was loosing and get lantern to get out. Press the lantern and i start the annimation to fly of. At the same time im in the midle of an AA and somehow manage to press close to lantern after pressing it, and instead of flying of with lantern i do a kalista dash ending up dying, lantern was gone (aka used).

Intentional or bug?