click to move error

Hello, I'm trying to implement the mouse-click movement on my rpg, i studied this script and it seems good aparently, but when i will run the game appears that error

"NullReferenceException UnityEngine.Camera.ScreenPointToRay (Vector3 position)"

the problem is in the code or in the object and your coordenates, or whatever ?

 public float PlayerMoveSpeed;
 private Vector3 TargetPosition;
 private Transform PlayerTransform;
  
  
 void Start () 
 {
     PlayerTransform = transform;
     TargetPosition = PlayerTransform.position;
 }
  
 void Update () 
 {          
     //Amount to move, move speed
     float amtToMove = PlayerMoveSpeed * Time.deltaTime;
  
     //Move the Player after they have clicked the Left Mouse Button on a location
     if (Input.GetMouseButtonDown(0))
     {
        Plane playerPlane = new Plane(Vector3.up, PlayerTransform.position);
         Ray ray = Camera.main.ScreenPointToRay(Input.mousePosition);
         float hitdist = 0.0f;
  
        if (playerPlane.Raycast(ray, out hitdist)) 
        {
             Vector3 targetPoint = ray.GetPoint(hitdist);
             TargetPosition = ray.GetPoint(hitdist);
             Quaternion targetRotation = Quaternion.LookRotation(targetPoint - transform.position);
             PlayerTransform.rotation = targetRotation;
        }               
     }
  
     PlayerTransform.position = Vector3.Lerp(PlayerTransform.position, TargetPosition, amtToMove);
 }
 }