"Object reference not set to an instance of an Object"

So, I did post a similiar question not long ago. I am trying to make a script that makes it possible to instantiate a gameobject that follows the raycast hit position, and that I am able to rotate around the Y axis. So far this is what I have got:

 var rotation = Quaternion.identity;
             
 if (!isInstantiated && Input.GetMouseButtonDown(1))
 {
     Debug.Log("Object instantiated and held");
     var temp = Instantiate(bScript.shelterPrefabMarker, hit.point, rotation);
     isInstantiated = true;
     isPlacing = true;
 
 if (isPlacing)
 {
     //Code that makes the building marker follow the raycast hit
     
     if (Input.GetKeyDown(KeyCode.Q))
         temp.transform.eulerAngles = Vector3(10, 5, 0);
     
     if (Input.GetKeyDown(KeyCode.E))
         temp.transform.eulerAngles = Vector3(10, -5, 0);
     
     if (Input.GetKeyDown(KeyCode.E) || !tSwitch.holdHammer)
     {
         Debug.Log("Object released");
         isPlacing = false;
         isInstantiated = false;
     }
 }

Do you have any ideas how I should do to be able to make the gameobject follow my raycast hit position (I've tried moving it with temp.transform.position but it refuses to work), and how I can make the Q and E rotation work? Any help would be very appreciated! Thanks a lot!