Destroyed GameObject but still trying to access it

EntryPoint.cs

 protected IEnumerator LoadAsync(string prf_path, Transform prt_tf, bool is_enable = true)
 {
 
     ResourceRequest res_req = Resources.LoadAsync<GameObject>(string.Format(prf_path, quality));
     res_req.priority = 0; // = ThreadPriority.Low;
     yield return res_req;
 
     if (res_req == null || res_req.asset == null)
     {
         res_req = Resources.LoadAsync<GameObject>(string.Format(prf_path, "HIGH"));
         res_req.priority = 0; // = ThreadPriority.Low;
         yield return res_req;
         Debug.LogFormat(prf_path, "HIGH");
     }
     else
     {
         Debug.LogFormat(prf_path, quality);
     }
 
     GameObject prf = res_req.asset as GameObject;
     GameObject obj = Instantiate(prf);
 
     obj.transform.SetParent(prt_tf);
     obj.transform.localScale = Vector3.one;
     obj.transform.localRotation = prf.transform.localRotation;
     obj.transform.localPosition = prf.transform.localPosition;
     obj.name = prf.name;
     yield return new WaitForEndOfFrame();
     obj.SetActive(is_enable);
 }

obj.SetActive(is_enable); when i click the error it's pointing me here

LOBBYUI: I have an option which is Option Rendering and Option Livestreaming. Now here's the problem . When i tried to run my program for the very first time and choose Option Livestreaming it will work then i'll logout then it will go back to my LobbyUI and choose the Option Rendering. Then this error will come out

Object of type 'GameObject' has been destroyed but you are still trying to access it.

Now when i tried this line of code

 if (obj != null)
     {
         obj.SetActive(is_enable);
     }

It will point out to my object which is initiated and that's pretty weird . Any idea?

MORE INFO

I load my resources using this line of code: MC_EntryPoint: EntryPointA

 if (PlayerPrefs.GetInt(OptionPopup.LiveStreaming_) == 1)
     {
         tf = transform.Find("UI Root/FullscreenPanel/Screen3DUI/panel (depth 1~2)");
         yield return StartCoroutine(LoadAsync("MC_VERSION/{0}/UI/Screen3DUI/logo", tf));
         yield return StartCoroutine(LoadAsync("MC_VERSION/{0}/UI/Screen3DUI/card_open_window", tf));
         yield return StartCoroutine(LoadAsync("MC_VERSION/{0}/UI/Screen3DUI/ranking", tf));
         yield return StartCoroutine(LoadAsync("MC_VERSION/{0}/UI/Screen3DUI/streaming_feed", tf));
 
         tf = transform.Find("UI Root/FullscreenPanel/Screen3DUI/panel (depth 10~11)");
         yield return StartCoroutine(LoadAsync("MC_VERSION/{0}/UI/Screen3DUI/midterm_loading", tf));
 
         tf = transform.Find("UI Root/FullscreenPanel/Screen3DUI/panel (depth 12)");
         yield return StartCoroutine(LoadAsync("MC_VERSION/{0}/UI/Screen3DUI/game_result", tf));
     }
     else
     {
         yield return StartCoroutine(LoadAsync("MC_VERSION/{0}/UI/Screen3DUI/minimap_type_b (x_ 1575, 1356)", tf));
         yield return StartCoroutine(LoadAsync("MC_VERSION/{0}/UI/Screen3DUI/replay", tf));
 
         tf = transform.Find("UI Root/FullscreenPanel/Screen3DUI/panel (depth 1~2)");
         yield return StartCoroutine(LoadAsync("MC_VERSION/{0}/UI/Screen3DUI/logo", tf));
         yield return StartCoroutine(LoadAsync("MC_VERSION/{0}/UI/Screen3DUI/card_open_window", tf));
         yield return StartCoroutine(LoadAsync("MC_VERSION/{0}/UI/Screen3DUI/ranking", tf));
         yield return StartCoroutine(LoadAsync("MC_VERSION/{0}/UI/Screen3DUI/top_bar", tf));
 
         tf = transform.Find("UI Root/FullscreenPanel/Screen3DUI/panel (depth 10~11)");
         yield return StartCoroutine(LoadAsync("MC_VERSION/{0}/UI/Screen3DUI/midterm_loading", tf));
 
         tf = transform.Find("UI Root/FullscreenPanel/Screen3DUI/panel (depth 12)");
         yield return StartCoroutine(LoadAsync("MC_VERSION/{0}/UI/Screen3DUI/game_result", tf));
     }
 
     loading.SetValue(0.02f);    // 2%.

So it's something like . Is there any other way load some of my UserInterface if i'm from Livestreaming(which i do not load some UI) to Rendering (which i load some UI)

EntryPointA:EntryPoint

 protected override IEnumerator Init()
 {
     tzPlayInfo.Instance.BLOCK_GAME_FLOW = true;
     tzPlayInfo.Instance.MAKING_GAME_OBJECT = true;
     //start_time = Time.realtimeSinceStartup;
     loading.SetValue(0f);       // 0%.
 
     yield return StartCoroutine(InitSystem());
     //Debug.Log(string.Format("End InitSystem - {0}s", Time.realtimeSinceStartup - start_time));
     loading.SetValue(0.01f);    // 1%.
 
     yield return StartCoroutine(InitUI());
     //Debug.Log(string.Format("End InitUI - {0}s", Time.realtimeSinceStartup - start_time));
     loading.SetValue(0.05f);    // 5%.
 
     yield return StartCoroutine(InitGO());
     //Debug.Log(string.Format("End InitGO - {0}s", Time.realtimeSinceStartup - start_time));
     loading.SetValue(0.95f);    // 95%.
 
     yield return StartCoroutine(InitServerDependentInfo());
     //Debug.Log(string.Format("End InitServerDependentInfo - {0}s", Time.realtimeSinceStartup - start_time));
     loading.SetValue(0.96f);    // 96%.
 
     yield return StartCoroutine(Recheck());
     //Debug.Log(string.Format("End Recheck - {0}s", Time.realtimeSinceStartup - start_time));
     loading.SetValue(1f);       // 100%.
     CameraManager.Instance.TurnOnCamera(eCmr.PADDOCK_1); // 로딩이 끝나면 카메라를 켠다.
     tzPlayInfo.Instance.BLOCK_GAME_FLOW = false;
 
     Destroy(loading.gameObject);   
     Destroy(this);             // EntryPoint 
 }

And i'm guessing that it is null because I destroy something??? Please enlighten me.