Fix si no viene ponSerialNumber como parameter en request

src/FTTHBundle/Admin/ONUAdmin.php

@@ -104,7 +104,11 @@ class ONUAdmin extends WorkflowBaseAdmin
                 }
                 
                 $ponSerialNumber = $this->getRequest()->query->get('psn');
-                $form->add('ponSerialNumber', null, array('data' => $ponSerialNumber));
+                if ($ponSerialNumber) {
+                    $form->add('ponSerialNumber', null, array(
+                        'data' => $ponSerialNumber,
+                    ));
+                }
             }
         );        
     }