Strange "Null or not an object" error in IE

IE reports: Error: 'parent_name' is null or not an object

for line 3 in the below code:

populate(default_parent, jQuery('#categoryParent').get(0), jQuery.map(categories, function (cat) {
        return {
            name: cat.parent_name,
            value: cat.parent_slug
        }
    }));

Deleting the above chunk of code, the error goes away, so definitely the source of the error is here.

The categories object is like:

var categories = [
    { parent_slug:"real_estate", parent_name:"Ακίνητα", childs: [
                        {child_slug: "homes", child_name: "Σπίτια"},
                        {child_slug: "apartments", child_name: "Διαμερίσματα"},                                     ]},
    { parent_slug:"jobs", parent_name:"Εργασ开发者_运维知识库ία", childs: [
                        {child_slug: "restaurant_food_service_jobs", child_name: "Εστιατόρια"},
...];

Everything works well in FF, Chrome, etc.

Presuming this is the full code, I think the error is probably in the syntax you are using for setting categories. You have arrays and objects with trailing commas, e.g.

var myArray = ['item1', 'item2',];
var myObject = {foo: 'item1', bar: 'item2',}

This is accepted by all browsers except IE. Try again with the trailing commas removed.