ok

app/Http/Controllers/QuickApp/Book/BookController.php

@@ -104,7 +104,7 @@ class BookController extends BaseController
             return response()->error('QAPP_SYS_ERROR');
         }
         if (!in_array($book_info->is_on_shelf, [2])) {
-            return response()->error('QAPP_OFF  _SHELF');
+            return response()->error('QAPP_OFF_SHELF');
         }
         $is_on_shelf = UserShelfBooksService::getUserShelfBooksListByUidAndBid($this->uid, $bid);
         $book_info['is_on_user_shelf'] = 0;