I am having a problem with my RaycastShooting script.

I just recently watched one of brackeys tutorials and used his script. I get this error code only when I run the game: NullReferenceException: Object reference not set to an instance of an object RaycastShooting.Update () (at Assets/Scripts/Player/RaycastShooting.js:9).

Here is the script: #pragma strict

var Effect : Transform; var TheDammage = 100;

function Update () {

 var hit : RaycastHit;
 var ray : Ray = Camera.main.ScreenPointToRay(Vector3(Screen.width*0.5, Screen.height*0.5, 0));
 
 if (Input.GetMouseButtonDown(0))
 {
     if (Physics.Raycast (ray, hit, 100))
     {
         var particleClone = Instantiate(Effect, hit.point, Quaternion.LookRotation(hit.normal));
         Destroy(particleClone.gameObject, 2);
         hit.transform.SendMessage("ApplyDammage", TheDammage, SendMessageOptions.DontRequireReceiver);
     }
 }
 

}

Thank you!