Enemy AI Script

I have this script that makes the enemy follow the player, but for some reason i keep getting errors and i don't know why.

 var target : GameObject; //the enemy's target
 var moveSpeed = 3; //move speed
 var rotationSpeed = 3; //speed of turning
 var range : float=10f;
 var range2 : float=10f;
 var stop : float=0;
 var myTransform : Transform; //current transform data of this enemy
 function Awake()
 {
     myTransform = transform; //cache transform data for easy access/preformance
 }
  
 function Start()
 {
      target = target.GameObject; //target the player
  
 }
  
 function Update () {
     //rotate to look at the player
     var distance = Vector3.Distance(myTransform.position, target.position);
     if (distance<=range2 &&  distance>=range){
     myTransform.rotation = Quaternion.Slerp(myTransform.rotation,
     Quaternion.LookRotation(target.position - myTransform.position), rotationSpeed*Time.deltaTime);
     }
  
  
     else if(distance<=range && distance>stop){
  
     //move towards the player
     myTransform.rotation = Quaternion.Slerp(myTransform.rotation,
     Quaternion.LookRotation(target.position - myTransform.position), rotationSpeed*Time.deltaTime);
     myTransform.position += myTransform.forward * moveSpeed * Time.deltaTime;
     }
     else if (distance<=stop) {
     myTransform.rotation = Quaternion.Slerp(myTransform.rotation,
     Quaternion.LookRotation(target.position - myTransform.position), rotationSpeed*Time.deltaTime);
     }
  
  
 }

This is the error i get...

 NullReferenceException: Object reference not set to an instance of an object
 Boo.Lang.Runtime.RuntimeServices.GetDispatcher (System.Object target, System.String cacheKeyName, System.Type[] cacheKeyTypes, Boo.Lang.Runtime.DynamicDispatching.DispatcherFactory factory)
 Boo.Lang.Runtime.RuntimeServices.GetDispatcher (System.Object target, System.Object[] args, System.String cacheKeyName, Boo.Lang.Runtime.DynamicDispatching.DispatcherFactory factory)
 Boo.Lang.Runtime.RuntimeServices.GetProperty (System.Object target, System.String name)
 UnityScript.Lang.UnityRuntimeServices.GetProperty (System.Object target, System.String name)
 Enemy AI.Update () (at Assets/Scripts/Enemy AI.js:21)

How can i fix this?