--- module_filter_tab.js (saved version)
+++ (current document)
@@ -220,15 +220,17 @@
     hash = 'all';
   }
 
-  if (Drupal.ModuleFilter.activeTab != undefined) {
-    Drupal.ModuleFilter.activeTab.element.removeClass('selected');
-  }
+  if (Drupal.ModuleFilter.tabs[hash + '-tab']) {
+    if (Drupal.ModuleFilter.activeTab != undefined) {
+      Drupal.ModuleFilter.activeTab.element.removeClass('selected');
+    }
 
-  Drupal.ModuleFilter.activeTab = Drupal.ModuleFilter.tabs[hash + '-tab'];
-  Drupal.ModuleFilter.activeTab.element.addClass('selected');
+    Drupal.ModuleFilter.activeTab = Drupal.ModuleFilter.tabs[hash + '-tab'];
+    Drupal.ModuleFilter.activeTab.element.addClass('selected');
 
-  var moduleFilter = $('input[name="module_filter[name]"]').data('moduleFilter');
-  moduleFilter.applyFilter();
+    var moduleFilter = $('input[name="module_filter[name]"]').data('moduleFilter');
+    moduleFilter.applyFilter();
+  }
 };
 
 Drupal.ModuleFilter.eventHandlerOperateByURLFragment = function(event) {