title: aframe error: Entity.setObject3D was called with an object that was not an instance of THREE.Object3D
body: <p>hello i've tried to add a mesh to my aframe component, but i receive a strange error also with a very simple code like this</p>
  
  <pre><code>AFRAME.registerComponent('mysquare', {
        init: function(){
          var el = this.el; 
  
          var box = new THREE.BoxGeometry(40, 5, 40);
          var boxMesh = new THREE.Mesh(box);
          boxMesh.position.set(25, 0, 25);
          el.setObject3D("mesh", boxMesh);
  
        }
      });
  </code></pre>
  
  <p>home.html</p>
  
  <pre><code>&lt;ion-content&gt;
        &lt;div&gt;&lt;/div&gt;
        &lt;a-scene embedded&gt;
           &lt;a-entity mysquare&gt;&lt;/a-entity&gt;
         &lt;/a-scene&gt; 
  &lt;/ion-content&gt;
  </code></pre>
  
  <p>error message</p>
  
  <blockquote>
    <p>Error: <code>Entity.setObject3D</code> was called with an object that was not an instance of <code>THREE.Object3D</code>.</p>
  </blockquote>
  
  <p>i tried also the <code>add</code> function but i receive the same message. how is possible?</p>
  
  <p>i develop my app with ionic 2 + aframe v.0.7.1. i've tried also with the 0.5.0 version but i have the same problem</p>