Make sure the model was loaded before we attempt to remove the mesh (#5499)

Fixes #4139

Co-authored-by: Antonio Pisano <apisano@wu.ac.at>

Author: Elettrotecnica

src/components/obj-model.js

@@ -34,11 +34,11 @@ module.exports.Component = registerComponent('obj-model', {
   },
 
   remove: function () {
-    if (!this.model) { return; }
     this.resetMesh();
   },
 
   resetMesh: function () {
+    if (!this.model) { return; }
     this.el.removeObject3D('mesh');
   },