I need help with a NullReferanceException problem

I was following a guide to make a simple game and followed everything almost perfectly but for some reason i get 3 seperate NullReferanceException's

NullReferenceException: Object reference not set to an instance of an object enemyPatrol.Start () (at Assets/scripts/enemyPatrol.cs:12)

NullReferenceException: Object reference not set to an instance of an object enemyPatrol.Update () (at Assets/scripts/enemyPatrol.cs:21)

and

NullReferenceException: Object reference not set to an instance of an object enemyPatrol.Update () (at Assets/scripts/enemyPatrol.cs:21) UnityEditor.Toolbar:OnGUI()

Here's the script it's coming from

using UnityEngine;

using System.Collections;

public class enemyPatrol : MonoBehaviour {

 public Transform [] patrolPoints;

 public float moveSpeed;

 private int currentPoint;

 // Use this for initialization
 void Start () 
 {
     transform.position = patrolPoints [0].position;
     currentPoint = 0;
 
 }
 
 // Update is called once per frame
 void Update () {
     
     
     if (transform.position == patrolPoints [currentPoint].position)
     {    
         currentPoint++;//++ adds 1 to amount
     }


     if (currentPoint >= patrolPoints.Length) 
     {
         currentPoint = 0;
     }
                             
     transform.position = Vector3.MoveTowards (transform.position, patrolPoints [currentPoint].position, moveSpeed * Time.deltaTime);
 
 }

}

It's attached to an enemy cube wich just has to move around but when i press play it just keeps pausing it and showing the errors mentioned above. If there is any more info i should give to help please tell me. Thanks!