truly fixed registration

src/middlewares/existance.js

@@ -20,7 +20,7 @@ const usernameDoesntExist = async (req, res, next) => {
         let { username } = req.body;
 
         let user = await UserService.getByUsername(username);
-        if (user != statuses.not_found) return res.status(400).send("Such username already taken");
+        if (user != undefined && user != statuses.not_found) return res.status(400).send("Such username already taken");
         next();
     } catch (e) { return res.status(500).send(log.unknownError(`${TAG}/usernameDoesntExist: ${e}`)); }
 }