fix weird backend bug

backend/src/api.js

@@ -11,7 +11,10 @@ export class ApiError extends Error {
 }
 
 const router = Router();
-const asyncHandler = fn => (req, res, next) => Promise.resolve(fn(req, res, next)).catch(next);
+const asyncHandler = fn => (req, res, next) => Promise.resolve(fn(req, res, next)).catch(err => {
+    res.error = err;
+    next();
+});
 
 const userSchema = Joi.object({
     username: Joi.string().min(3).max(32).required()

backend/src/index.js

@@ -48,7 +48,8 @@ app.use("/api/docs", swaggerUi.serve, swaggerUi.setup(specs));
 app.use("/api", apiRouter);
 
 // has to be last
-app.use((err, _req, res) => {
+app.use((_req, res, _next) => {
+  const err = res.error;
   if (err instanceof ApiError) {
     return res.status(err.status).json({ status: "error", error: err.message });
   }