Loading a new scene in unity make OVRManager throws errors

I have never tried having those in every scene so I can't answer on that. I have a GameManager script attached to CameraHolder object as a singleton do not destroy object. I don't even use OVRManager or the OVRCameraRig to keep code compatible with non-oculus versions. I use a normal camera with a TrackedPoseDriver added to the same object like in the image. However should I add OVRManager and OVRCameraRig it would be to the CameraHolder object.

In my Awake() in GameManager I setup everything once and keep it when switching between scenes (I only have two scenes, Menu and Game). Maybe this can give you some ideas at least.

 using UnityEngine;
 using UnityEngine.SceneManagement;
 using UnityEngine.XR;
 using UnityEngine.InputSystem;
 using System.Threading;
 public static GameManager theGM = null;
 public CameraController theCameraHolder;

 //first code to run
 void Awake()
 {
     //singleton
     if (theGM == null)
     {
         theGM = this;
     }
     else if (theGM != this)
     {
         //enforce singleton pattern, meaning there can only ever be one instance of a GameManager.
         Destroy(gameObject); //<- this makes OnDestroy() be called and
         //we don't want to deinit everything there (leave it empty).
         return;
     }

     //the rest is done once only...
     DontDestroyOnLoad(gameObject);

     bool bInited = InitOculus();

     if (!bInited)
     {
         bNoVR = true;
         Screen.SetResolution(1280, 720, true);
         Debug.Log("Error initing VR, continue with no VR");
     }
     else
     {
         Screen.SetResolution(864, 960, false);
     }

     //set thread prio
     UnityEngine.Application.backgroundLoadingPriority = UnityEngine.ThreadPriority.BelowNormal;
     Thread.CurrentThread.Priority = System.Threading.ThreadPriority.AboveNormal;

     //init to black screen
     theCameraHolder.InitForMenu();
     oFadeMatCopy = new Material(oFadeMat);
     oFadeBox.GetComponent<MeshRenderer>().material = oFadeMatCopy;
     StartFade(0.01f, 0.0f, true);

     //set audio out setting
     if (!bNoVR) AudioStateMachine.instance.SetOutputByRiftSetting();
     AudioSettings.OnAudioConfigurationChanged += AudioSettings_OnAudioConfigurationChanged;
 }

 private void AudioSettings_OnAudioConfigurationChanged(bool deviceWasChanged)
 {
     if (!bNoVR) AudioStateMachine.instance.SetOutputByRiftSetting();
     else AudioStateMachine.instance.SetOutput(0);
 }

 //start of oculus specific code
 bool InitOculus()
 {
     try
     {
         Core.AsyncInitialize("200555...."); //appid
         Entitlements.IsUserEntitledToApplication().OnComplete(EntitlementCallback);
         Users.GetLoggedInUser().OnComplete(LoggedInUserCallback);
     }
     catch (UnityException e)
     {
         Debug.LogException(e);
         UnityEngine.Application.Quit();
     }

     bOculusDevicePresent = true;
     return true;
 }

 void EntitlementCallback(Message msg)
 {
     if (msg.IsError)
     {
         Debug.LogError("Not entitled to play this game");
         UnityEngine.Application.Quit(); //it is possible to remove quit while developing
     }
     else
     {
         Debug.Log("You are entitled to play this game");
     }
 }

 void LoggedInUserCallback(Message msg)
 {
     if (msg.IsError)
     {
         Debug.LogError("No Oculus user");
     }
     else
     {
         //save ID, and user name
         szUserID = msg.GetUser().ID.ToString();
         szUser = msg.GetUser().OculusID;
         Debug.Log("You are " + szUser);
         bUserValid = true;
     }
 }