Пишет NullReferenceException: Object reference not set to an instance of an object Platform. Что делать>?

Question

[BRIOONI]

Скрипт:

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

public class Platform : MonoBehaviour
{
    public float forceJump;                                       

    public void OnCollisionEnter2D(Collision2D collision)           
    {
        if (collision.relativeVelocity.y < 0)                       
        {
            Doodle.instance.DoodleRigid.velocity = Vector2.up * forceJump;    
        }        
    }
     
}

Ошибка: NullReferenceException: Object reference not set to an instance of an object
Platform.OnCollisionEnter2D (UnityEngine.Collision2D collision) (at Assets/Scripts Game/Platform.cs:13)