Unity crashes

 Collider2D[] colliders = Physics2D.OverlapCircleAll(_enemy.transform.position, 3f, LayerMask.GetMask("Enemy"));
         foreach(Collider2D nearbyObject in colliders)
         {
             Vector2 direction = (nearbyObject.transform.position - _enemy.transform.position);
             Vector2 directionNormal = direction.normalized; ;
             Rigidbody2D rb = nearbyObject.GetComponent<Rigidbody2D>();
             if (rb != null)
                 Debug.LogError("RB found");
             rb.AddForce(30f*directionNormal, ForceMode2D.Impulse);
 
             Enemy nearEnemy = rb.GetComponent<Enemy>();
             nearEnemy.DamageEnemy(40f);
 
 
         }

First off all, I'm finding the near enemy object colliders with Physics2D.OverlapCircleAll function and I can access their rigidbodies with their colliders and add force to them successfully. But when I'm trying to access them as enemies and damage them with my DamageEnemy function w$$anonymous$$ch only changes enemies' current health, Unity is cras$$anonymous$$ng and closing by itself. I don't know what I'm doing wrong. Please help me.