Ok, thaks for the clarification. It happend 2 times when I changed from the human to the drone, that's why I had thought that it was a bug. Maybe to make it clear you should put an out of ammo sound? It would be nice if you put also some healing particles when the drone gets healed with the tools. I think it would fit well if the zombies can't hit the drone and put batteries to recharge it's power. You could make that it moves faster when it has full battery and slower when has only a little.
You could also make the out of ammo weapons disappear because when you have 5 or 6 where the player is it's very difficult to pick up one with bullets. Maybe just make that you pick first the weapons with ammo?
When you have been playing for a little if you try to pick up something with the drone, it doesn't pick up anything and the human does, maybe a bug?
Sorry if I have been too harsh in the previous comment