fix sidebar active element highlighting (close hasura#21)

Author: EAtrey

src/components/sidebar/treeNode.js

@@ -4,7 +4,7 @@ import ClosedSvg from '../images/closed';
 import config from '../../../config';
 import Link from "../link";
 
-const TreeNode = ({className = '', setCollapsed, collapsed, url, title, items, location, ...rest}) => {
+const TreeNode = ({className = '', setCollapsed, collapsed, url, title, items, location = document.location, ...rest}) => {
   const isCollapsed = collapsed[url];
   const collapse = () => {
     setCollapsed(url);