Adding Instantiated Objects to ArrayList but it returns null C#

Well it's even before that. Right after I instantiate and add to the ArrayList I could do something like I did with Debug.Log("Temp is null" + tempObstacle == null); and it would return true stating that index is null.

If Instantiate returns null, then something went wrong there. Did you assign GameObjects to all the entries in obstacleTypes, like with the Inspector?

So I now have it actually assigning the indexes but now I can't destroy the object in the scene. I even tried a test where it would change the position of the obstacle to where the camera is so I know it is accessing the object. Here's what I'm now doing in the destroy area

obstacleBounds = new Vector3(0, cameraTransform.position.y + Screen.height, 0);

     try
     {
         foreach(Obstacle obs in obstaclesInSceneList)
         {
             if(obs.transform.position.y > obstacleBounds.y)
             {
                 obs.isActive = false;    
                                                                                     //Test code 
                                                                                     //obs.transform.position = cameraTransform.position
                                        //Destroy (obs); //Creates an error since it can't 
                                                                                    //access the next object in the arraylist
             }
             
         }
         
         for(int j = 0; j < obstaclesInSceneList.Count; j++)
         {
             if(obstaclesInSceneList[j] is Obstacle)
             {
                 Obstacle tempObstacle = (Obstacle)obstaclesInSceneList[j];
                 if(!tempObstacle.isActive)
                 {
                 Destroy((Obstacle)obstaclesInSceneList[j]);
                     
                 obstaclesInSceneList.RemoveAt(j);    
                                Debug.Log ("Removed: " + j);
                                Destroy (tempObstacle);
                     
                 Debug.Log("Destroyed: " + j);
                 }
             }
         }
         
     
     
     }
     catch($$anonymous$$issingReferenceException e)
     {
         Debug.Log(e.ToString());    
     }

I don't understand why it won't destroy the obstacle

btw, foreach doesn't work either. The enumerator of the ArrayList or List class will check the version of the List which is incremented if you change anything, even when you assign a value to an existing element. Generally there are two ways to iterate through a list when you want to remove elements:

• Use a while loop and increment the count variable only when you didn't remove an element this iteration.

• Count backwards. That's the easiest way, but you have to be careful with the bounds.

  for(int j = obstaclesInSceneList.Count-1; j >= 0; j--) {

I'm trying the backwards for loop but still nothing. Here's the current code for it.

obstacleBounds = new Vector3(0, cameraTransform.position.y + Screen.height, 0);

     try
     {
         for(int j = obstaclesInSceneList.Count-1; j >= 0; j--)
         {
             if(obstaclesInSceneList[j] is Obstacle)
             {
                 if(((Obstacle)obstaclesInSceneList[j]).transform.position.y > obstacleBounds.y)
                 {
                     Destroy((Obstacle)obstaclesInSceneList[j]);
                     obstaclesInSceneList.RemoveAt(j);
                     continue;
                 }
                 
             }
         }    
     }
     catch($$anonymous$$issingReferenceException e)
     {
         Debug.Log(e.ToString());    
     }