Fix for sidebar searching when there are no sidebar to search (#3010)

* added examples for box shadows

Add some examples for shadows on certain elements/widgets like the cards or tables; mainly to help with color contrasting since the body background has a similar color / tone with the element/widget's background

* Revert "added examples for box shadows"

This reverts commit 3aa62588db.

* Fix sidebar searching

If there are no data-widget: "sidebar-search" found, then stop init()

build/js/SidebarSearch.js

@@ -61,6 +61,10 @@ class SidebarSearch {
   // Public
 
   init() {
+    if ($(SELECTOR_DATA_WIDGET).length == 0) {
+      return
+    }
+
     if ($(SELECTOR_DATA_WIDGET).next(SELECTOR_SEARCH_RESULTS).length == 0) {
       $(SELECTOR_DATA_WIDGET).after(
         $('<div />', { class: CLASS_NAME_SEARCH_RESULTS })