Not Found Error vs Return Null w/ handlers

error_api.js

var facade = require('facade'),
    handlers = require('handlers');

app.use("/verification/:verificationId", funciton (req, res) {
  facade.getUserForVerificationId(req.params.verificationId)
    .then(handlers.successHandler, handlers.errorHandler);
});

error_facade.js

module.exports = {
  getUserForVerificationId: getUserForVerificationId
}

function getUserForVerificationId(verificationId) {
  return db.filter({verificationId: verificationId}).one()
    .then(function (user) {
      if (!user) {
        return Promise.rejected(new NotFoundError("User not found by verification:" + verificationId));
      }
      return user;
    });
}

error_handlers.js

module.exports = {
  errorHandler: errorHandler,
  successHandler: successHandler
}

function errorHandler(err, res) {
  if (err instanceof NotFoundError) {
    return res.send(404);
  }
  return res.send(500);
}

function successhandler(result, res) {
  res.send(200, res);
}

null_api.js

var facade = require('facade'),
    handlers = require('handlers');

app.use("/verification/:verificationId", funciton (req, res) {
  facade.getUserForVerificationId(req.params.verificationId)
    .then(handlers.notFoundIfNullHandler, handler.errorHandler);
});

null_facade.js

module.exports = {
  getUserForVerificationId: getUserForVerificationId
}

function getUserForVerificationId(verificationId) {
  return db.filter({verificationId: verificationId}).one();
}

null_handlers.js

module.exports = {
  getResponseHandler: getResponseHandler,
  notFoundIfNullHandler: notFoundIfNullHandler
}

function notFoundIfNullHandler(result, res) {
  if (result == null) {
    return res.send(404);
  }
  return res.send(200, result);
}

function errorHandler(err, res) {
  res.send(500);
}