Boxcollider 2D Destroyed

I am making a metroidvania game and its going really but when ever i collect a power up i get this error The object of type 'BoxCollider2D' has been destroyed but you are still trying to access it. How do i fix it because it works perfectly just how i want it the only thing is i get the error, my code(its attached to my player) CAN ANSWERS BE IN JAVA SCRIPT ONLY:

 #pragma strict
 
 var Speed : float = 12;
 var Health : float = 100;
 
 //Items and ability variables
 var ShowLabelSuperboots : boolean = false;
 var ShowLabelLaserblaster : boolean = false;
 var ShowLabelMegaBoots : boolean = false;
 var ShowLabelGevar : boolean = false;
 
 var Skin : GUISkin;
 var AbilityLabelTime : float = 3;
 var CollectedGun : boolean = false;
 var StopTime : float = 3;
 
 //Bullet variables
 public var bulletRight : GameObject;
 public var bulletLeft : GameObject;
 
 function Update () 
 {
 
 //Jump
 if (Input.GetKey (KeyCode.W))  
     {
         transform.Translate(Vector3(0,Speed,0) * Time.deltaTime);
     }
     
 //Move left
 if (Input.GetKey (KeyCode.A)) 
     {
         transform.localScale.x = 1;
         transform.Translate(Vector3(-Speed,0,0) * Time.deltaTime);
     }
     
 //Move right
 if (Input.GetKey (KeyCode.D)) 
     {
         transform.localScale.x = 1;
         transform.Translate(Vector3(Speed,0,0) * Time.deltaTime);
     }
      
 //Shoot right     
 if (CollectedGun == true){ 
      if(Input.GetKey(KeyCode.RightArrow)) { 
          Instantiate(bulletRight, transform.position, Quaternion.identity);
     }
 }
     
 //Shoot left    
          if (CollectedGun == true){ 
       if (Input.GetKey(KeyCode.LeftArrow)) {
           Instantiate(bulletLeft, transform.position, Quaternion.identity);
         }
     }
 }
 
 function OnTriggerEnter2D (other : Collider2D) {
  
 //Super speed power up
      if (other.gameObject.tag == "SuperSpeed") {    
           ShowLabelSuperboots = true;
          Speed = Speed + 8;
          Destroy(other.gameObject);
          yield WaitForSeconds(AbilityLabelTime); ShowLabelSuperboots = false; 
      }
      
 //Laserblaster power up     
      if (other.gameObject.tag == "Laserblaster") {
          CollectedGun = true;
          ShowLabelLaserblaster = true;
          Destroy(other.gameObject);        
          yield WaitForSeconds(AbilityLabelTime); ShowLabelLaserblaster = false; 
      }
      
 //Megaspeed power up     
      if (other.gameObject.tag == "MegaSpeed") {
          ShowLabelMegaBoots = true;
          Destroy(other.gameObject);
         Speed = Speed + 10;                 
          yield WaitForSeconds(AbilityLabelTime); ShowLabelMegaBoots = false; 
      }
      
 //Gevar suit power up     
      if (other.gameObject.tag == "Gevar") {
          ShowLabelGevar = true;
          Destroy(other.gameObject);
          
          yield WaitForSeconds(AbilityLabelTime); ShowLabelGevar = false;
      }
  }
  
  function OnGUI()  {
      GUI.skin = Skin;
      
      //Label Super Boots
      if (ShowLabelSuperboots){
           GUI.Label(Rect(100,100,Screen.width,Screen.height),"Super Boots Acquired - These let you move and jump faster"); 
       }
       
       //Label Laserblaster
       if (ShowLabelLaserblaster){
           GUI.Label(Rect(100,100,Screen.width,Screen.height),"Laser Blaster Acquired - This lets you shoot with the arrow keys");
       }
       
       //Label Mega Boots
       if (ShowLabelMegaBoots){
           GUI.Label(Rect(100,100,Screen.width,Screen.height),"Mega Boots Acquired - These let you move and jump even faster");
       }
       
       //Label Gevar Suit
       if (ShowLabelGevar){
           GUI.Label(Rect(100,100,Screen.width,Screen.height),"Gevar Suit Acquired - Protects you from lava");
       }
  }