Error message from console after destroying an Object ?

Whats up guys , First of all I’m new to Unity so please If my problem is so obvious don’t Judge me , Second,I had a Logical Problem I guess , The game is about a cannon that shoot balls to destroy objects , when the target get hit it will give red color,destroy and re-spawn in a new random location…

the problem is I got a console error message shows after the object get destroyed and it bugs me to find the reason.

here is the Image of the ball script (the cannon ball is a prefab) :

And Here is and Image of the console message that shows ONLY after the object get destroyed in game :

You must have other script witch want access to destroy object.