[backend] Facture : debug "type de montant inconnu"

common/models/Order.php

                                         - $this->getAmountWithTax(self::AMOUNT_TOTAL);
                                 break;
                         default:
-                                throw new NotFoundHttpException('Type de montant inconnu.') ;
+                                throw new NotFoundHttpException('Type de montant inconnu : '.$type) ;
                 }
 
                 if ($format) {