Hello everyone I have got some trouble with script of BallController

Unity Engine
1

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

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

please help me to fix that.
Full code :

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class BallController : MonoBehaviour {
    [SerializeField]
    private float speed;
    bool started;
    Rigidbody rb;
    bool gameOver;

    void Awake()
    {
        rb = GetComponent<Rigidbody>();
     
    }
    // Use this for initialization
    void Start () {
        started = false;
        gameOver = false;
    }
 
    // Update is called once per frame
    void Update () {

        if(!started)
        {
            if(Input.GetMouseButtonDown (0))
            {
                rb.velocity = new Vector3(speed, 0, 0);
                started = true;
            }
        }

        Debug.DrawRay(transform.position, Vector3.down, Color.red);

       if(!Physics.Raycast (transform.position, Vector3.down, 1f))
        {
            gameOver = true;
            rb.velocity = new Vector3(0, -25f, 0);
         
                Camera.main.GetComponent<CameraFollow>().gameOver = true;
         
        }

        if(Input.GetMouseButtonDown (0) && !gameOver)
        {
            SwitchDirection ();
        }
    }

    void SwitchDirection ()
    {
        if (rb.velocity.z > 0)
        {
            rb.velocity = new Vector3(speed, 0, 0);
        }
        else if (rb.velocity.x > 0)
        {
            rb.velocity = new Vector3(0, 0, speed);
        }
    }
}

Full Script for camera follow

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class CameraFollow : MonoBehaviour {

    public GameObject ball;
    Vector3 offset;
    public float lerpRate;
    public bool gameOver;

    // Use this for initialization
    void Start () {
        offset = ball.transform.position - transform.position;
        gameOver = false;
    }
 
    // Update is called once per frame
    void Update () {
        if (!gameOver)
        {
            follow();
        }
    }

    void follow()
    {
        Vector3 pos = transform.position;
        Vector3 targetPos = ball.transform.position - offset;
        pos = Vector3.Lerp(pos, targetPos, lerpRate * Time.deltaTime);
        transform.position = pos;
    }
}

I will be very grateful.

2

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