【解決方法】このエラーが発生しました：

using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using UnityEngine.SceneManagement;
using UnityEngine.UI;

public class player_good : MonoBehaviour
{
    public float speed ;
    public float JumpForce;
    Rigidbody2D rb;
    bool OnGround;
    private Animator anim;
    SpriteRenderer sprite;
    [SerializeField] private Text counter;
    [SerializeField]private AudioSource jumpSoundeffect;
    [SerializeField]private AudioSource collectSoundeffect;
    [SerializeField]private AudioSource endSoundeffect;
    private int count=0;
    // Start is called before the first frame update
    void Start()
    {
        rb=GetComponent<Rigidbody2D>();
        OnGround=true;
        sprite = GetComponent<SpriteRenderer>();
        anim=GetComponent<Animator>();
    }
    // Update is called once per frame
    void Update()
    {
        float player =Input.GetAxis("Horizontal");
        transform.position += new Vector3(player*speed,0,0);
        if (Input.GetKeyDown(KeyCode.Space)&&OnGround)
        {
             jumpSoundeffect.Play();
             rb.AddForce(new Vector2(0,JumpForce));
             anim.SetTrigger("jump");
        }
        //flipping
        if (player>0)
        {
            sprite.flipX=false;
        }
        else if (player<0)
        {
            sprite.flipX=true;
        }
        if(player!=0)
        {
           anim.SetBool("is wolking",true);
        }
        else
        {
           anim.SetBool("is wolking",false);
        }
    }
    private void OnCollisionEnter2D(Collision2D collision)
    {
       if (collision.gameObject.tag=="Ground")
       {
         OnGround=true;
       }
       if (collision.gameObject.CompareTag("end"))
       {
         endSoundeffect.Play();
         SceneManager.LoadScene("SampleScene");
       }

      
    }
    private void OnCollisionExit2D(Collision2D collision)
    {
       if (collision.gameObject.tag=="Ground")
       {
          OnGround=false;
       }
    }
   	private void OnTriggerEnter2D (Collider2D collision)
   	{
   	    if(collision.gameObject.CompareTag("fruit"))
   	    {
   	         collectSoundeffect.Play();
   	       	 count++;
   	    	 Destroy(collision.gameObject);
   	    	 counter.text="Fruits"+count;

   	    }
   	}

}

私が試したこと：

I got this error :
ArgumentNullException: Value cannot be null.
 Parameter name: source 
UnityEngine.AudioSource.Play () (at <6d9b197a0b824e1d8ee671e1e014c4d1>:0) player_good.Update () (at Assets/player_good.cs:35)