Issue #1829328 by Christian Biggins, larowlan | falcon03: Fixed Adding a new content type, 'default parent item' is shown even if no menu is selected.

core/modules/menu/menu.admin.js

@@ -32,14 +32,19 @@ Drupal.menuUpdateParentList = function () {
       var selected = $select.val();
       // Remove all exisiting options from dropdown.
       $select.children().remove();
-      // Add new options to dropdown.
+      // Add new options to dropdown. Keep a count of options for testing later.
+      var totalOptions = 0;
       for (var machineName in options) {
         if (options.hasOwnProperty(machineName)) {
           $select.append(
             $('<option ' + (machineName === selected ? ' selected="selected"' : '') + '></option>').val(machineName).text(options[machineName])
           );
+          totalOptions++;
         }
       }
+
+      // Hide the parent options if there are no options for it.
+      $select.closest('div').toggle(totalOptions > 0).attr('hidden', totalOptions === 0);
     }
   });
 };