错误 MissingReferenceException：“GameObject”类型的 object 已被破坏，但您仍在尝试访问它

Question

I have been making a 2D game in Unity. I'm trying to make a game over screen appear every time a ball touches the player. I also added advertisements to release it. I added Restart and Continue buttons. When you press continue, an ad shows and the game continues. When Restart is pressed, it resets the game and your score. Whenever I restart the game and then press continue, the ad is played, but the game does not continue.

Here is the collision script:

using UnityEngine;

public class hitDetect : MonoBehaviour
{

    public GameObject menuContainer;

    private void OnTriggerEnter2D(Collider2D other)
    {
        Debug.Log("HIT");
        menuContainer.SetActive(true);
        Time.timeScale = 0;
    }

}

This is the script that restarts the game:

using UnityEngine;
using UnityEngine.SceneManagement;
public class RestartGame : MonoBehaviour
{
    public void Restart()
    {
        SceneManager.LoadScene(SceneManager.GetActiveScene().buildIndex);
        Time.timeScale = 1;
    }
}

Here is the advertisement and continue script:

using UnityEngine;
using UnityEngine.Advertisements;

public class continueGame : MonoBehaviour, IUnityAdsListener
{
    string placement = "rewardedVideo";
    public GameObject menuContain;

    private void Start()
    {
        Advertisement.AddListener(this);
        Advertisement.Initialize("4006857", true);
    }

    
    public void Continue(string p)
    {
        Advertisement.Show(p);
    }

    public void OnUnityAdsReady(string placementId)
    {

    }

    public void OnUnityAdsDidError(string message)
    {

    }

    public void OnUnityAdsDidStart(string placementId)
    {

    }

    public void OnUnityAdsDidFinish(string placementId, ShowResult showResult)
    {
        if(showResult == ShowResult.Finished)
        {
            menuContain.SetActive(false);
            Time.timeScale = 1;
        }
    }
}

Answer 1

Once you call

SceneManager.LoadScene(SceneManager.GetActiveScene().buildIndex)

a "new" scene is loaded and therefore anything currently existing is destroyed.

In continueGame you do

private void Start()
{
    Advertisement.AddListener(this);
    Advertisement.Initialize("4006857", true);
}

But you never remove that listener!

Thus the next time the Advertisement fires its event it is still trying to execute them of the now already destroyed continueGame instance.

---

Therefore you always should remove any listeners as soon as you don't need them anymore:

private void OnDestroy ()
{
    Advertisement.RemoveListener(this);
}