Fixes bug in actions creating for search facet

In case that there are no actions specified in spec object, the concatenation
of arrays causes that 'undefined' item is added into the array.

https://pagure.io/freeipa/issue/7052

Reviewed-By: Petr Vobornik <pvoborni@redhat.com>

install/ui/src/freeipa/search.js

@@ -63,7 +63,7 @@ exp.search_facet_control_buttons_pre_op = function(spec, context) {
     var default_actions = ['refresh', 'batch_remove', 'add'];
     var merged_actions = override_actions(spec.custom_actions, default_actions);
 
-    spec.actions = merged_actions.concat(spec.actions);
+    spec.actions = merged_actions.concat(spec.actions || []);
     spec.control_buttons = spec.control_buttons || [];
 
     if (!spec.no_update) {