Error handler middleware is not running in express app

Question

The error is being handled by express inbuilt error handler. But I want it to run my custom handler on catch of an error. Here is the code: miscellaneousAPI.js:

router.get("/exception", async (req, res, next) => {
  try {
    let ele = {};
    //delibrately causing an error.
    const ele2 = ele.map((i) => i);
    res.status(200).send({ data: ele2 });
  } catch (error) {
    next(error);
  }
});

app.get("/", (req, res) => {
  res.status(200).send({ status: "ok" });
});
app.use((req, res) => {
  res.status(404).send({
    error: true,
    message: "This route is not defined. Please try specified ones.",
  });
});
app.use((error, req, res) => {
  const errMsg = error.message || "Something went wrong";
  res.status(error.statusCode).json({
    success: false,
    status: error.statusCode,
    message: errMsg
  });
});

I tried other answers on internet but my code is correct according to those. Please help me.