Why won't my shooting script work?

I created a script for shooting in unity. In a basic sense I made it to where I can set a specific number of bullets that can be shot ,how long they last, and when to destroy them. I also added in for the bullets to return back into the hierarchy after being used. I receive an error message
“The object of type ‘GameObject’ " has been destroyed but you are still trying to access it. Script should either check if null or you shouldn’t destroy the object.” even though I told it to return after it had been destroyed.

Here is the section of the script that is said “incorrect.”

 public GameObject GetBullet() {
        foreach (GameObject bullet in bullets) {
            if (!bullet.activeInHierarchy) {
                bullet.SetActive (true);
                return bullet;

Destroyed is not the same thing as setting a gameObject as not active. Destroyed literally means destroyed. It’s gone and all references to it are wiped out.