Custom error handling

 USING TRY-CATCH BLOCK

app.post("/listings", async (req, res,next) => {

  try {

    const newListing = new Listing(req.body.listing);

    await newListing.save();

    res.redirect("/listings");

  } catch (err) {

    next(err);

  }

});app.use((err,req, res, next) => {

  res.send("error occured");

});