_Container addChild function is not working properly

[pnongah]

We get a refNode is null at line 42 as shown below:

		addChild: function(/*dijit/_WidgetBase*/ widget, /*int?*/ insertIndex){
			// summary:
			//		Makes the given widget a child of this widget.
			// description:
			//		Inserts specified child widget's dom node as a child of this widget's
			//		container node, and possibly does other processing (such as layout).

			// I want to just call domConstruct.place(widget.domNode, this.containerNode, insertIndex), but the counting
			// is thrown off by text nodes and comment nodes that show up when constructed by markup.
			// In the future consider stripping those nodes on construction, either in the parser or this widget code.
			var refNode = this.containerNode;
			if(insertIndex > 0){
				// Old-school way to get nth child; dojo.query would be easier but _Container was weened from dojo.query
				// in #10087 to minimize download size.   Not sure if that's still and issue with new smaller dojo/query.
				refNode = refNode.firstChild;
		/* line 42 */   while(insertIndex > 0){
					if(refNode.nodeType == 1){ insertIndex--; }
					refNode = refNode.nextSibling;
				}
				if(refNode){
					insertIndex = "before";
				}else{
					// to support addChild(child, n-1) where there are n children (should add child at end)
					refNode = this.containerNode;
					insertIndex = "last";
				}
			}

A simple solution to that would be to check for refNode in the "while" as follow:

/* line 42 */ while(refNode && insertIndex > 0)

[bill]

Duplicate of #16874.
Presumably you have passed illegal arguments to addChild(), although I can't say for sure without a test case.