MissingReferenceException: The object of type 'Script' has been destroyed but you are still trying to access it.

Oops guys. I know this error is pretty much the most common Unity error... I have been programming in Unity for 2 years and now I have a game project, however, the mechanics of hitting the enemy is not working when he is Instantiated for the 2nd time or when the scene is reloaded. I honestly don't know what to do and I hope your help. Here are some error files.

Attack Box Script (It is activated at a moment of the attack animation)

 public sealed class PlayerAttackArea : MonoBehaviour
 {
     private int _damageValue;
     private GameObject objHit; 
     public delegate void DealDamage(int damage, GameObject obj); 
     public static event DealDamage OnEnemyHit;
 
     private void Start()
     {
         this._damageValue = GetComponentInParent<Player>()._damageValue; 
     }
     
     private void OnTriggerEnter2D(Collider2D other)
     {
         objHit = other.gameObject;
         if (OnEnemyHit != null) 
         {   
             OnEnemyHit(_damageValue, objHit);
             print("Something Hit");
             objHit = null;
         } else if (OnEnemyHit == null)              
         {
             print("Event not found");
         }
     } 
 }

Function script that is returning an error. Remembering that I'm using events to communicate between scripts.

     private void IWasHit(int damageValue, GameObject obj)
     {
         if (obj == gameObject)
         {
             print(obj.name+" Foi Acertado");
             TakeDamage(damageValue);
         }
     }

That method in turn asks for another method of a class being inherited. Now finally the error that is returned.

I'm Brazilian, I used google translator to send a message, I hope you understood