Error handler not working properly. Getting empty array instead to error in Express,Node,Mongoose API application

I am working on an API application where I am using Express, Node, and Mongoose. When I am trying findById(req.params.id)my error handler works as expected.

   exports.getProductByCustId = async(req, res, next) => {
  try {
  const products = await Product.findById(req.params.id);
  if (!products) {
    // When ID is correct but not available in database
    return next(`Products not found with id of ${id}`, 404);
  }
  res.status(200).json(products);
  catch(err) {
   next(err);
  }
};

But when I do like this, it works:

  exports.getProductByCustId = async(req, res, next) => {
  const id = req.params.id;
  let cutomerId = { cust_id: id };
  const products = await Product.find(customerId, {_id: 0, __v: 0, cust_id: 0});
  console.log(products);
  if (!products) {
    // When ID is correct but not available in database
    return next(new ErrorResponse(`Products not found with id of ${id}`, 404));
  }
  res.status(200).json(products);
};

My error handler not working and getting "[]" every time if customerId is incorrect or

I will be really thankful if anyone can help. I already tried all the possible slack channel but no luck so far. I will thankful if anyone can help.