Question Null Reference!

Hi, I keep getting null reference on this code! The funny thing is, it was working fine unity today morning, and when I tired playing it later without changing any code, it now throws a null reference. I have stated the variable/value in update, and then updated the slider value in late update, but it still throws a null reference. I have tried different ways, but it doesn't work.

Code (CSharp):

1. public Slider HealthSlider;
2.     [HideInInspector]
3.     public float Health;
4.     private GameObject Warden;
5.     public  BlightBehaviours BlightBehaviours;
6.     void Start()
7.     {
8.         Warden = GameObject.Find("BlightWarden");
9.     }
10.     private void Update()
11.     {
12.      
13.    
14.         Health = BlightBehaviours.Hitpoints;
15.  
16.     }
17.  
18.     // Update is called once per frame
19.     void LateUpdate()
20.     {
21.         HealthSlider.value = Health; // this part throws a null reference, it was working fine before!
22.  
23.  
24.  
25.     }
26.     public void DestroySlider()
27.     {
28.         Destroy(gameObject);
29.     }

 

Ensure that HealthSlider has been assigned in the inspector.

Also check that you haven't accidentally added a second copy of your script somewhere (search t:<scriptname>) in the hierarchy search.

 

I have checked that HealthSlider is in the correct place and there is no duplicate script, but it still throws a null reference exception :|

 

I literally did nothing and it works again! ???? Do you know why ??