Iterating Through a Tree of Ember-Data async Records

I'm trying to iterate through a tree of Ember-Data async records. The function crash of line 5 when children[i] has no children. How could I verify if children exist in children[i]? Or could you provide a better iterating function?

traverse: function(scsLink) {
  console.log(scsLink.id);
  scsLink.get('children').then(children => {
    for(var i in children) {
      children[i].get('children').then(_children => {
        this.traverse(children[i]);
      });
    }
  });
},