[Solved] Find the bug in this middleware snippet:const mw = (req, res, next) => { if (req.isValid) next; else res.status(400).send('Bad Request'); } | NestJS

NestJS - Middleware

Find the bug in this middleware snippet:

const mw = (req, res, next) => { if (req.isValid) next; else res.status(400).send('Bad Request'); }

Anext is not called as a function

Bres.status() is missing a send() call

Creq.isValid should be req.valid

DMiddleware must be a function declaration

Step-by-Step Solution

Solution:

Step 1: Check how next is used
next is referenced but not called as next().
Step 2: Effect of missing parentheses
Without parentheses, next() is not executed, blocking request flow.
Final Answer:
next is not called as a function -> Option A
Quick Check:
Call next() with parentheses [OK]

Quick Trick: Always call next() with parentheses [OK]

Common Mistakes:

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