feat: use void widget, so methods always return a widget

core/modules/widgets/void.js

@@ -0,0 +1,49 @@
+/*\
+title: $:/core/modules/widgets/Void.js
+type: application/javascript
+module-type: widget
+
+Void widget that is not intended for render.
+
+\*/
+(function(){
+
+/*jslint node: true, browser: true */
+/*global $tw: false */
+"use strict";
+
+var Widget = require("$:/core/modules/widgets/widget.js").widget;
+
+var VoidNodeWidget = function(parseTreeNode,options) {
+	this.initialise(parseTreeNode,options);
+};
+
+/*
+Inherit from the base widget class
+*/
+VoidNodeWidget.prototype = new Widget();
+
+/*
+Render this widget into the DOM
+*/
+VoidNodeWidget.prototype.render = function(parent,nextSibling) {
+	// Nothing to do for a void node
+};
+
+/*
+Compute the internal state of the widget
+*/
+VoidNodeWidget.prototype.execute = function() {
+	// Nothing to do for a void node
+};
+
+/*
+Selectively refreshes the widget if needed. Returns true if the widget or any of its children needed re-rendering
+*/
+VoidNodeWidget.prototype.refresh = function(changedTiddlers) {
+	return false;
+};
+
+exports.void = VoidNodeWidget;
+
+})();

core/modules/widgets/widget.js

@@ -554,7 +554,7 @@ Widget.prototype.makeChildWidget = function(parseTreeNode,options) {
 	if(!WidgetClass) {
 		WidgetClass = this.widgetClasses.text;
 		// Skip void node that is not intended for render. Show error for missing widgets.
-		parseTreeNode = {type: "text", text: parseTreeNode.void ? "" : "Undefined widget '" + parseTreeNode.type + "'"};
+		parseTreeNode = {type: "text", text: "Undefined widget '" + parseTreeNode.type + "'"};
 	}
 	// Create set variable widgets for each variable
 	$tw.utils.each(options.variables,function(value,name) {