I'm having trouble placing a Dojo widget in th

I've got a simple widget:

define(["dojo/_base/declare", "dijit/_WidgetBase", "dojo/dom-construct"],
function(declare, WidgetBase, domConstruct){

    return declare("gijit.workflow.debug.combi", [WidgetBase], {
        startup: function(){
            alert("started");
        },
        buildRendering: function(){

            var container = domConstruct.create("div", {innerHTML:"test"}, this.domNode, "first");
            var rad1 = domConstruct.create("input", {type:"radio"}, container, "first");
            var rad1 = domConstruct.create("input", {type:"radio"}, container, "last");
        }
    });
});

and a simple loading page:

<!DOCTYPE html>
<html >
<head>

<link rel="stylesheet" href="../../../css/tcs-style-dijit.css" />

<script>dojoConfig = {parseOnLoad: false}</script>
<script src="../../../js/dojo/dojo.js" data-dojo-config="async: true"></script>
<!-- <script src="../../../js/gijit/workflow/debug/combi.js"></script> -->
<script>
require(["dojo/dom", "gijit/workflow/debug/combi", "dojo/parser",
        "dojo/_base/window"], function(dom, combi, parser, window) {
    var widget = new combi();
    widget.placeAt(window.body());
//  widget.startup();
});
</script>
</head>
<body id="dd" class="tcs">
</body>
</html>

However, I get the following error:

Component returned failure code: 0x80004003 (NS_ERROR_INVALID_POINTER) [nsIDOMHTMLBodyElement.appendChild] domain">http://domain: port/js/dojo/dojo.js Line 15

I have isolated the error to the point where I try to place the widget in the HTML:

widget.placeAt(window.body());

I am unable to figure out what is causing the issue, and would appreciate some help

At the moment you invoke window.body() the DOM has not been parsed yet and it therefore returns undefined. Require dojo/domReady! plugin as the last module loading:

require([
    "dojo/dom",
    "gijit/workflow/debug/combi",
    "dojo/parser",
    "dojo/_base/window",
    "dojo/domReady!"  // ==> wait for the DOM to be ready
], function(dom, combi, parser, win) {
    var widget = new combi();
    widget.placeAt(win.body());
    widget.startup();
});

Please note, that as a best practice I would recommend not to hide window object by assigning dojo/_base/window module into a local window variable, use win instead.