Webservice: Fix optional parameter and improve exception when missing required parameter - refs BT#20290

Author: @BorjaSanchezBeezNest

main/inc/lib/webservices/Rest.php

@@ -2827,7 +2827,7 @@ class Rest extends WebService
      *
      * @return array e.g: [ { "id": 4, "title": "aiken", "updated_by": "-", "type": "1", "completion": 0 } ]
      */
-    public function getTestAverageResultsList(array $ids = [], array $fields = []): array
+    public function getTestAverageResultsList(array $ids = [], ?array $fields = []): array
     {
         self::protectAdminEndpoint();
         $tableTrackExercises = Database::get_main_table(TABLE_STATISTIC_TRACK_E_EXERCISES);
@@ -2845,9 +2845,10 @@ class Rest extends WebService
             if (!is_array($fields)) {
                 $fields = [$fields];
             }
-
-            foreach ($fields as $field) {
-                $extraArray[$field] = '';
+            if (!empty($fields)) {
+                foreach ($fields as $field) {
+                    $extraArray[$field] = '-';
+                }
             }
 
             $queryUsersInCourses = "

main/webservices/api/v2.php

@@ -817,9 +817,13 @@ try {
             );
             break;
         case Rest::GET_TEST_AVERAGE_RESULTS_LIST:
+            if (empty($_POST['ids'])) {
+                throw new Exception(get_lang('NoData'));
+            }
             Event::addEvent(LOG_WS.$action, 'success', 'true');
+            $fields = $_POST['fields'] ?? [];
             $restResponse->setData(
-                $restApi->getTestAverageResultsList($_POST['ids'], $_POST['fields'])
+                $restApi->getTestAverageResultsList($_POST['ids'], $fields)
             );
             break;
         default: