Hello everyone I have got some trouble with script of BallController

Error is "NullReferenceException: object reference not set to an instance of an object"
Unity tells me , trouble in the string

Code (CSharp):

1. Camera.main.GetComponent<CameraFollow>().gameOver = true;

please help me to fix that.
Full code :

Code (CSharp):

1. using System.Collections;
2. using System.Collections.Generic;
3. using UnityEngine;
4.  
5. public class BallController : MonoBehaviour {
6.     [SerializeField]
7.     private float speed;
8.     bool started;
9.     Rigidbody rb;
10.     bool gameOver;
11.  
12.     void Awake()
13.     {
14.         rb = GetComponent<Rigidbody>();
15.      
16.     }
17.     // Use this for initialization
18.     void Start () {
19.         started = false;
20.         gameOver = false;
21.     }
22.  
23.     // Update is called once per frame
24.     void Update () {
25.  
26.         if(!started)
27.         {
28.             if(Input.GetMouseButtonDown (0))
29.             {
30.                 rb.velocity = new Vector3(speed, 0, 0);
31.                 started = true;
32.             }
33.         }
34.  
35.         Debug.DrawRay(transform.position, Vector3.down, Color.red);
36.  
37.        if(!Physics.Raycast (transform.position, Vector3.down, 1f))
38.         {
39.             gameOver = true;
40.             rb.velocity = new Vector3(0, -25f, 0);
41.          
42.                 Camera.main.GetComponent<CameraFollow>().gameOver = true;
43.          
44.         }
45.  
46.         if(Input.GetMouseButtonDown (0) && !gameOver)
47.         {
48.             SwitchDirection ();
49.         }
50.     }
51.  
52.     void SwitchDirection ()
53.     {
54.         if (rb.velocity.z > 0)
55.         {
56.             rb.velocity = new Vector3(speed, 0, 0);
57.         }
58.         else if (rb.velocity.x > 0)
59.         {
60.             rb.velocity = new Vector3(0, 0, speed);
61.         }
62.     }
63. }
64.  

Full Script for camera follow

Code (CSharp):

1. using System.Collections;
2. using System.Collections.Generic;
3. using UnityEngine;
4.  
5. public class CameraFollow : MonoBehaviour {
6.  
7.     public GameObject ball;
8.     Vector3 offset;
9.     public float lerpRate;
10.     public bool gameOver;
11.  
12.     // Use this for initialization
13.     void Start () {
14.         offset = ball.transform.position - transform.position;
15.         gameOver = false;
16.     }
17.  
18.     // Update is called once per frame
19.     void Update () {
20.         if (!gameOver)
21.         {
22.             follow();
23.         }
24.     }
25.  
26.     void follow()
27.     {
28.         Vector3 pos = transform.position;
29.         Vector3 targetPos = ball.transform.position - offset;
30.         pos = Vector3.Lerp(pos, targetPos, lerpRate * Time.deltaTime);
31.         transform.position = pos;
32.     }
33. }
34.  

I will be very grateful.

 

Show please screenshot of your game in editor , especially inspector with Main Camera selecting, because i think there is no CameraFollow script on your camera