NullReferenceException: Object reference not set to an instance of an object BulletScript.Update () (at Assets/Scripts/BulletScript.js:8)

Hello :D

I'm a beginner in Unity so I need some help

I'm trying to make a first person shooter for a school project. I was trying to add in bullet holes and then I've encountered this problem and I have no idea on how to solve it...

I was hoping if you guys are able to help me.

NullReferenceException: Object reference not set to an instance of an object BulletScript.Update () (at Assets/Scripts/BulletScript.js:8)

Here is the script:

 var maxDist : float = 1000000000;
 var decalHitWall : GameObject;
 var floatInFrontOfWall : float = 0.00001;
 
 function Update ()
 {
     var hit : RaycastHit;
     if (Physics.Raycast(transform.position, transform.foward, hit, maxDist))
     {
         if (decalHitWall && hit.transform.tag == "Level Parts")
             Instantiate(decalHitWall, hit.point + (hit.normal * floatInFrontOfWall), Quaternion.LookRotation(hit.normal));
     }
 }

Thank you in advance :D