Error when changing another script's variable

Unity Engine
1

So, in my Player.cs file I have the following variable

public int score;

Now, on the Enemy.cs file (that handles the enemy behavior), I want to change the Player.cs’ score variable depending on the condition.

Here’s the Enemy.cs code:

public Player MyPlayer;

    private void OnTriggerEnter2D(Collider2D other)
    {
        if (other.tag == "PlayerShield")
        {
            MyPlayer.score++;
            destroyEnemy();
        }
        else if (other.tag == "Player")
        {
            MyPlayer.life -= 1;
            MyPlayer.score += 1;
            destroyEnemy();

        }
    }

    private void destroyEnemy()
    {
        Instantiate(_explosionAnimation, transform.position, Quaternion.identity);
        Destroy(this.gameObject);
    }

The problem is that, whenever a colision happens, I get the following error that points to the lines where I tried to call the Player.cs’ variable(s):
NullReferenceException: Object reference not set to an instance of an object

2

You need to assign a value to MyPlayer, most likely by dragging the object containing the player script into the MyPlayer slot on this script.

3

There is an empty slot there, yes, but I can’t drag anything into it.

4

You can drag in any object that has a MyPlayer script attached to it.

5

In the end, what I had to do was

public Player MyPlayer;

MyPlayer = GameObject.Find("Player").GetComponent<Player>();

But anyhow, thank you for your time.