Fixed problem with access to uninitialised array element

extension/qfq/qfq/form/FormAction.php

@@ -91,7 +91,7 @@ class FormAction {
 
             // Preparation for Log, Debug
             $this->store->setVar(SYSTEM_FORM_ELEMENT, Logger::formatFormElementName($fe), STORE_SYSTEM); // debug
-            $this->store->setVar(SYSTEM_FORM_ELEMENT_ID, $fe[FE_ID], STORE_SYSTEM); // debug
+            $this->store->setVar(SYSTEM_FORM_ELEMENT_ID, $fe[FE_ID]??'', STORE_SYSTEM); // debug
 
             $fe = HelperFormElement::initActionFormElement($fe);
 
@@ -153,7 +153,7 @@ class FormAction {
                     break;
                 default:
                     // Always work on recent data: previous actions might have modified the data.
-                    $this->store->fillStoreWithRecord($this->primaryTableName, $recordId, $this->db, $this->formSpec[F_PRIMARY_KEY]);
+                    $this->store->fillStoreWithRecord($this->primaryTableName, $recordId, $this->db, $this->formSpec[F_PRIMARY_KEY]??'');
             }
 
             if (!$this->checkRequiredList($fe)) {