modifying dragrigidbody script

Hello, i have been trying to make the drag rigidbody script work without a camera this meant i have to change some lines of code but i have gotten stuck at a particular point, i want to know how to achieve the same effect by using a different method.

i am trying to drag the rigid body(ragdoll) with an object(dragger) and i am stuck at this point in the code

 var dir  = Vector3.zero;// direction of the object to be dragged
 var target = Vector3.zero; // position of the object
 var myTransform: Transform;
 
 function Awake()
 {
       myTransform = transform; // for better performance
 }
 function Update ()
 {
     var dir = target - myTransform.position;
     Debug.DrawRay(myTransform.position, dir, Color.green);
     // Make sure the user pressed the mouse down
     if (!Input.GetMouseButtonDown (0))
         return;
     // check if the ragdoll can be carried    
     if(target == null)
     return;
     
     
     // We need to actually hit an object
     var hit : RaycastHit;
     if (!Physics.Raycast(myTransform.position,dir,  hit, 100))
         return;
     // We need to hit a rigidbody that is not kinematic
     if (!hit.rigidbody || hit.rigidbody.isKinematic)
         return;
     
     if (!springJoint)
     {
         var go = new GameObject("Rigidbody dragger");
         var body : Rigidbody = go.AddComponent ("Rigidbody") as Rigidbody;
         springJoint = go.AddComponent ("SpringJoint");
         body.isKinematic = true;
     }
     
     springJoint.transform.position = hit.point;
     if (attachToCenterOfMass)
     {
         var anchor = transform.TransformDirection(hit.rigidbody.centerOfMass) + hit.rigidbody.transform.position;
         anchor = springJoint.transform.InverseTransformPoint(anchor);
         springJoint.anchor = anchor;
     }
     else
     {
         springJoint.anchor = Vector3.zero;
     }
     
     springJoint.spring = spring;
     springJoint.damper = damper;
     springJoint.maxDistance = distance;
     springJoint.connectedBody = hit.rigidbody;
     
     StartCoroutine ("DragObject", hit.distance);
 }
 
 function DragObject (distance : float)
 {
     var oldDrag = springJoint.connectedBody.drag;
     var oldAngularDrag = springJoint.connectedBody.angularDrag;
     springJoint.connectedBody.drag = drag;
     springJoint.connectedBody.angularDrag = angularDrag;
     while (Input.GetMouseButton (0))
     {
 // the current code i am using
         var ray = new Ray (myTransform.positon, myTransform.forward);
 //var ray = main
         //var ray: Ray;
         springJoint.transform.position = ray.GetPoint(distance);
         yield;
     }
     if (springJoint.connectedBody)
     {
         springJoint.connectedBody.drag = oldDrag;
         springJoint.connectedBody.angularDrag = oldAngularDrag;
         springJoint.connectedBody = null;
     }
 }

it gives me null exception reference anytime i run it NullReferenceException: Object reference not set to an instance of an object dragPrey+$DragObject$38+$.MoveNext () (at Assets/myScripts/dragPrey.js:83) UnityEngine.MonoBehaviour:StartCoroutine(String, Object) dragPrey:Update() (at Assets/myScripts/dragPrey.js:72)

please i would like to know what is wrong with code above thanks.