added active menu item check before offset calculation

Author: ryancyq

aspnet-core/src/AbpCompanyName.AbpProjectName.Web.Mvc/wwwroot/js/admin.js

@@ -124,8 +124,11 @@ $.AdminBSB.leftSideBar = {
 
             //Scroll active menu item when page load, if option set = true
             if ($.AdminBSB.options.leftSideBar.scrollActiveItemWhenPageLoad) {
-                var activeItemOffsetTop = $('.menu .list li.active')[0].offsetTop
-                if (activeItemOffsetTop > 150) $el.slimscroll({ scrollTo: activeItemOffsetTop + 'px' });
+                var $activeItem = $('.menu .list li.active');
+                if ($activeItem.length) {
+                    var activeItemOffsetTop = $activeItem[0].offsetTop;
+                    if (activeItemOffsetTop > 150) $el.slimscroll({ scrollTo: activeItemOffsetTop + 'px' });
+                }
             }
         }
     },
@@ -457,4 +460,4 @@ $(function () {
     $.AdminBSB.search.activate();
 
     setTimeout(function () { $('.page-loader-wrapper').fadeOut(); }, 50);
-});
+});