Помогите решить ошибку в юнити, пожалуйста.

Сделал скрипт в юнити, запусти и выдало такую ошибку: UnassignedReferenceException: The variable firePoint of FireBullet has not been assigned.
You probably need to assign the firePoint variable of the FireBullet script in the inspector.
UnityEngine.Transform.get_position () (at <b1fe495152fd4f0180f79e56e3bccacc>:0)
FireBullet.Update () (at Assets/Fire.cs:22)
Вот скрипт:
using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class FireBullet : MonoBehaviour
{
public GameObject bullet;
public Transform firePoint;

Rigidbody2D _rigidbody;

void Start()
{
_rigidbody = bullet.AddComponent<Rigidbody2D>();
}

// Update is called once per frame
void Update()
{
if (Input.GetButtonDown("Fire1"))
{
Instantiate(bullet, firePoint.position, firePoint.rotation);

_rigidbody.velocity = new Vector2(10 * Time.deltaTime, 0);
}
}
}
Подскажите, пожалуйста, как решить.