[Libraries] Feedback panel - fix fieldnames setting (#8848)

In the feedback panel for an instrument, the only option in 'Field Name' was 'Across all fields'. This changes how the field names for an instrument are fetched so that all of them appear as an option too.

php/libraries/BVL_Feedback_Panel.class.inc

@@ -101,7 +101,15 @@ class BVL_Feedback_Panel
         $summary = $this->feedbackThread->getSummaryOfThreads();
         $this->tpl_data['thread_summary_headers'] = json_encode($summary);
 
-        $field_names = Utility::getSourcefields($_REQUEST['test_name'] ?? '');
+        $test_name = '';
+        if (array_key_exists('test_name', $_REQUEST)) {
+            $test_name = $_REQUEST['test_name'];
+        } else if (array_key_exists('lorispath', $_REQUEST)) {
+            $test_name = preg_split("#/#", $_REQUEST['lorispath'])[1] ?? '';
+        }
+
+        // Get field names
+        $field_names = Utility::getSourcefields($test_name);
         $fields      = [];
         $fields['Across All Fields'] = 'Across All Fields';
         foreach ($field_names as $field_name) {