Merge pull request #1111 from CHU295/develop

fix~issues 1110

Author: anikethsaha

src/core/event/sidebar.js

@@ -39,6 +39,7 @@ export function collapse(el) {
     if (
       target.nodeName === 'A' &&
       target.nextSibling &&
+      target.nextSibling.classList &&
       target.nextSibling.classList.contains('app-sub-sidebar')
     ) {
       dom.toggleClass(target.parentNode, 'collapse');