still trying to access a destroyed transform...

hi i'm sorry if its a stupid question but i only asked because i couldn't solve it.

the error:MissingReferenceException: The object of type 'Transform' has been destroyed but you are still trying to access it. Your script should either check if it is null or you should not destroy the object. UnityEngine.Component.get_transform () (at C:/BuildAgent/work/7535de4ca26c26ac/Runtime/ExportGenerated/Editor/UnityEngineComponent.cs:21) RedSolder.WhereToLook () (at Assets/RedSolder.js:90) RedSolder.Update () (at Assets/RedSolder.js:26)

i know what the error means i just cant find out what part of the script its coming from, any help is appreciated

 #pragma strict
 var Health:float=10;
 var speed:float=1;
 var range:float=5;
 private var hit : RaycastHit;
 
 var wheretolook:Transform;
 
 private var lastUpdate:float=0;
 private var EnemyBase:GameObject;
 private var RotateSpeed:float=10;
 
 function Start () {
     
         EnemyBase=GameObject.FindWithTag("BlueBase");
         wheretolook=EnemyBase.transform;
 
 }
 
 function Update () {
         //defining the closest enemy few times a second
         var ClosestEnemy = Vector3.Distance(FindClosestEnemy().transform.position, transform.position);
         
         //always running these functions so the variables arnt null
         FindClosestEnemy();
         WhereToLook();
 
         
         Debug.DrawRay(transform.position , transform.forward * 8 , Color.white);
         //this is to avoid colliding and going throigh team mates
         if(Physics.Raycast(transform.position, transform.forward,hit, range)){
                 
                     //if its a team mate then rotate away
                      if(hit.transform.tag =="Red"){
                         RotateAway();
                     }
 
         }
         
 
         
         //if the enemy is closer then 8
          if(ClosestEnemy<8) {
          //and if hes in range then attack
             if(ClosestEnemy<=range){
                 Attack();
             }
             //if not in range then move in more
             else{
                 transform.Translate(Vector3.forward * speed * Time.smoothDeltaTime);
             }
             //this makes sure that we have something to look at        
             wheretolook=FindClosestEnemy().transform;
             
             
         }//if the enmey is not closer then 8 then move into their base
         else{
             transform.Translate(Vector3.forward * speed * Time.smoothDeltaTime);
             wheretolook=EnemyBase.transform;
         }
         //if we have nothing to look at then make the base the primary target
         if(wheretolook ==null){
             wheretolook=EnemyBase.transform;
             transform.Translate(Vector3.forward * speed * Time.smoothDeltaTime);
         }
         //this is self explanatory
         if(Health<=0){
         Destroy(this.gameObject);
         }
         
 }
 
 function RotateAway(){
 transform.Rotate(Vector3.up, -170*RotateSpeed* Time.smoothDeltaTime);
 }
 
 
 function WhereToLook(){
 
 var rotate = Quaternion.LookRotation(wheretolook.transform.position - transform.position);
     transform.rotation = Quaternion.Slerp(transform.rotation, rotate, Time.deltaTime *0.4);
 
 
 }
 
 function Attack(){
 
   if(Time.time - lastUpdate >= 1f){
   
         FindClosestEnemy().SendMessageUpwards("ApplyDamage", 1, SendMessageOptions.DontRequireReceiver);
         
         lastUpdate = Time.time;
     }
     
 }
 
 //thi is where other enemys call in to give damage
 function ApplyDamage (damage : float) {
     Health-=damage;
 }
     
 
         
 function FindClosestEnemy () : GameObject {
     
       // Find all game objects with tag Enemy
     var gos : GameObject[];
     gos = GameObject.FindGameObjectsWithTag("Blue"); 
     
       
         var closest : GameObject; 
         var distance = Mathf.Infinity; 
         var position = transform.position; 
         // Iterate through them and find the closest one
         for (var go : GameObject in gos)  { 
             var diff = (go.transform.position - position);
             var curDistance = diff.sqrMagnitude; 
             if (curDistance < distance) { 
                 closest = go; 
                 distance = curDistance; 
             } 
         } 
         return closest;    
     }