Can't edit built-in array through script unless viewed in Inspector

 class Data{
         public var x : float;
         public var y : float;
         public var z : float;
         public var name : String;
     }
     
     class DataClass{
        var allObjects:Data[] = new Data[0];
        function DataClass() { }
     }
     
     var objectData:DataClass;
     
     function Start(){
     
         var foundObjects = GameObject.FindObjectsOfType(Transform);
         objectData.allObjects = new Data[foundObjects.Length]; 
         yield WaitForSeconds(1);
         for(var num:int;num<foundObjects.Length;num++){
             objectData.allObjects[num].x = foundObjects[num].position.x; //Error here
             objectData.allObjects[num].y = foundObjects[num].position.y; 
             objectData.allObjects[num].z = foundObjects[num].position.z;
             objectData.allObjects[num].name = foundObjects[num].name; 
         }
     }    

When I run this and the objectData array isn't displayed in the Inspector, I get "NullReferenceException: Object reference not set to an instance of an object". This also happens if I remove the yield or make the array static or private.

If I select the gameobject with the script, so I can see the array in the Inspector, it works.