#558: + Error initializing

Sortable.js

@@ -172,6 +172,10 @@
 	 * @param  {Object}       [options]
 	 */
 	function Sortable(el, options) {
+		if (!(el && el.nodeType && el.nodeType === 1)) {
+			throw 'Sortable: `el` must be HTMLElement, and not ' + {}.toString.call(el);
+		}
+
 		this.el = el; // root element
 		this.options = options = _extend({}, options);