title: Why i have stage.height/width is 0 using PixiJS?
body: <p>In function setup the value of app.stage.height is 0. Why? There is a text for validator(zzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzz)</p>
  
  <pre><code>       let Application = PIXI.Application,
              Container = PIXI.Container,
              loader = PIXI.loader,
              resources = PIXI.loader.resources,
              TextureCache = PIXI.utils.TextureCache,
              Sprite = PIXI.Sprite,
              Rectangle = PIXI.Rectangle;
  
          let app = new Application({ 
              width: 512, 
              height: 512,                       
              antialias: true, 
              transparent: false, 
              resolution: 1
            }
          );
  
          document.body.appendChild(app.view);
  
          loader
            .add("/img/treasureHunter.json")
            .load(setup);
  
          function setup() {
            console.log(app.stage.height)
  
            let id = PIXI.loader.resources["/img/treasureHunter.json"].textures;
            let dungeon = new Sprite(id["dungeon.png"])
            let treasure = new Sprite(id["treasure.png"]);
            let explorer = new Sprite(id["explorer.png"]);
            explorer.y = app.stage.height / 2 - explorer.height / 2;
            console.log(app.stage.height)
            explorer.x = 68;
  
  
            app.stage.addChild(dungeon);
            app.stage.addChild(explorer);
            app.stage.addChild(treasure);
          }
  </code></pre>