Please, check out this tutorial: https://developer.playcanvas.com/en/tutorials/using-assets/
The code in this tutorial and script in the project: https://playcanvas.com/project/406036/overview/tutorial-asset-registry are different
The first one is using this.entity.model.asset to assign 3d models. But in the project it is this.entity.model.model.
Or is it alright to use both ways?