(mvc) check for uuid before using it.

src/opnsense/mvc/app/library/OPNsense/Base/UIModelGrid.php

@@ -70,6 +70,7 @@ class UIModelGrid
 
         $recordIndex = 0;
         foreach ($this->DataField->sortedBy($sortBy, $sortDescending) as $record) {
+            if (array_key_exists("uuid", $record->getAttributes())) {
                 // parse rows, because we may need to convert some (list) items we need to know the actual content
                 // before searching.
                 $row =  array();
@@ -112,6 +113,7 @@ class UIModelGrid
                     $recordIndex++;
                 }
             }
+        }
 
         $result['rowCount'] = count($result['rows']);
         $result['total'] = $recordIndex;