The Weapons, "10.Weapon/0"

Hello, I have a problem to solve the "10.Weapon/0". I attached the reason of the error (attachement1). When I ran my code in my local machine, it didn't show any error (attachment2). I think there is a problem when it tries to add 'Rookie' but I don't know the exact reason. Please help me to correct the error. I attached my code too (attachment3).