Game manager Object reference not set to an instance of an object

I was following along with a video about a scene manager and some other tips.

I am getting an error when I run it. "Object reference not set to an instance of an object" for the line with

 updateDelegates[(int)State.Reset] = UpdateSceneReset;

I am still fairly new to c# so I am having trouble finding out what reference is not set to an instance.

 using UnityEngine;
 using System.Collections;
 
 public class Manager : MonoBehaviour 
 {
     public static Manager manager;
     private string currentScene;
     private string nextScene;
     private AsyncOperation resourceUnload;
     private AsyncOperation sceneLoad;
     private enum State { Reset, Preload, Load, Unload, Post, Ready, Run, Count };
     private State state;
     private delegate void UpdateDelegate();
     private UpdateDelegate[] updateDelegates;
 
     // Use this for initialization
     public void Awake () 
     {
         Object.DontDestroyOnLoad(gameObject);
 
         manager = this;
             // the error is for the line below
         updateDelegates[(int)State.Reset] = UpdateSceneReset;
         updateDelegates[(int)State.Preload] = UpdateScenePreload;
         updateDelegates[(int)State.Load] = UpdateSceneLoad;
         updateDelegates[(int)State.Unload] = UpdateSceneUnload;
         updateDelegates[(int)State.Post] = UpdateScenePost;
         updateDelegates[(int)State.Ready] = UpdateSceneReady;
         updateDelegates[(int)State.Run] = UpdateSceneRun;
 
         nextScene = "Main Menu";
         state = State.Reset;
     }
 
     public static void SwitchScene(string scene)
     {
         if(manager != null)
         {
             if(manager.currentScene != scene)
             {
                 manager.nextScene = scene;
             }
         }
     }
     
     protected void Update()
     {
         if(updateDelegates[(int)state] != null)
         {
             updateDelegates[(int)state]();
         }
     }
 
     // GC old scene
     private void UpdateSceneReset()
     {
         System.GC.Collect();
         state = State.Preload;
     }
 
     // Start loading the new scene
     private void UpdateScenePreload()
     {
         sceneLoad = Application.LoadLevelAsync(nextScene);
         state = State.Load;
     }
 
     // load the scene and show load progress
     private void UpdateSceneLoad()
     {
         if(sceneLoad.isDone == true)
         {
             //sceneLoad = null; // ?
             state = State.Unload;
         }
         else 
         {
             // show progress
         }
     }
 
     private void UpdateSceneUnload()
     {
         if(resourceUnload == null)
         {
             resourceUnload = Resources.UnloadUnusedAssets();
         }
         else
         {
             if(resourceUnload.isDone == true)
             {
                 resourceUnload = null;
                 state = State.Post;
             }
         }
     }
 
     private void UpdateScenePost()
     {
         currentScene = nextScene;
         state = State.Ready;
     }
 
     private void UpdateSceneReady()
     {
         System.GC.Collect(); // dont use if you need loaded assets that are initially unused
         state = State.Run;
     }
 
     private void UpdateSceneRun()
     {
         if(currentScene != nextScene)
         {
             state = State.Reset;
         }
     }
 
     public void OnDestroy()
     {
         if(updateDelegates != null)
         {
             for(int i = 0; i < (int)State.Count; i++)
             {
                 updateDelegates[i] = null;
             }
             updateDelegates = null;
         }
 
         if(manager != null)
         {
             manager = null;
         }
     }
 }