Unity 5 Input.mousePosition NullReferenceException

Hello, I used this code in Unity 4 to rotate my player to the mouse position with a top view camera. But when i updated to Unity 5 it stopped working leaving me with a NullReferenceException error both in Javascript and C#

What would have to be modified so it works in Unity 5? Sorry for my bad English

   var speed = 4.0;
     
    function Update () {
    
        var playerPlane = new Plane(Vector3.up, transform.position);
     
    
        var ray = Camera.main.ScreenPointToRay (Input.mousePosition);
     
      
        var hitdist = 0.0;
    
        if (playerPlane.Raycast (ray, hitdist)) {
       
            var targetPoint = ray.GetPoint(hitdist);
     
         
            var targetRotation = Quaternion.LookRotation(targetPoint - transform.position);
     
            transform.rotation = Quaternion.Slerp(transform.rotation, targetRotation, speed * Time.deltaTime);
        }
    }

And here's the C# code

 using UnityEngine;
 using System.Collections;
 
 public class LookAtMouse : MonoBehaviour
 {
 
     // speed
     public float speed;
 
     void FixedUpdate()
     {
         Plane playerPlane = new Plane(Vector3.up, transform.position);
 
         Ray ray = Camera.main.ScreenPointToRay(Input.mousePosition);
 
         float hitdist = 0.0f;
   
         if (playerPlane.Raycast(ray, out hitdist))
         {
             Vector3 targetPoint = ray.GetPoint(hitdist);
             Quaternion targetRotation = Quaternion.LookRotation(targetPoint - transform.position);.
             transform.rotation = Quaternion.Slerp(transform.rotation, targetRotation, speed * Time.deltaTime);
         }
     }
 }