-fix unsused variable

src/exchange-tools/taler-exchange-offline.c

@@ -4259,13 +4259,14 @@ do_extensions_show (char *const *args)
        it = it->next)
   {
     const struct TALER_Extension *extension = it->extension;
+    int ret;
 
-    GNUNET_assert (0 ==
-                   json_object_set_new (exts,
-                                        it->extension->name,
-                                        it->extension->config_to_json (
-                                          it->extension)));
+    ret = json_object_set_new (exts,
+                               extension->name,
+                               extension->config_to_json (extension));
+    GNUNET_assert (-1 != ret);
   }
+
   obj = GNUNET_JSON_PACK (
     GNUNET_JSON_pack_object_steal ("extensions",
                                    exts));