[GAMEPLAY] Able to attack invulnerable towers

I was just playing an aram, and i was going to attack the nexus tower, but the inhib spawned just before i was in range. I didn't realize that it had spawned, especially because i was actually attacking the turret even though it's untargetable and invulnerable. I didn't deal any damage to it. I believe that i may have autoed at the exact moment the inhib respawned, but i'm not sure because i couldn't really see the inhib with how my screen was scrolled.