docs(cheatsheet): fix JS errors in setActiveItem() (#34011)

Author: ffoodd

site/content/docs/5.0/examples/cheatsheet/cheatsheet.js

@@ -25,8 +25,8 @@
       toast.show()
     })
 
-  // Disable empty links
-  document.querySelectorAll('[href="#"]')
+  // Disable empty links and submit buttons
+  document.querySelectorAll('[href="#"], [type="submit"]')
     .forEach(function (link) {
       link.addEventListener('click', function (event) {
         event.preventDefault()
@@ -41,6 +41,11 @@
     }
 
     var link = document.querySelector('.bd-aside a[href="' + hash + '"]')
+
+    if (!link) {
+      return
+    }
+
     var active = document.querySelector('.bd-aside .active')
     var parent = link.parentNode.parentNode.previousElementSibling