chore: 백엔드 에러 로깅 추가

src/index.js

@@ -15,11 +15,12 @@ app.use('/api', apiRouter);
 
 // eslint-disable-next-line no-unused-vars
 app.use((err, req, res, next) => {
+  console.error('failed to handle request', err);
+
   if (err instanceof ReportableError) {
     const { statusCode, message } = err;
     return res.status(statusCode).send({ statusCode, message });
   } else {
-    console.error('failed to handle request', err);
     return res
       .status(500)
       .send({ statusCode: 500, message: 'unhanlded error' });