refactor : app.js 수정

-let createError = require('http-errors');
-let express = require('express');
-let path = require('path');
-let cookieParser = require('cookie-parser');
-let logger = require('morgan');
+const createError = require('http-errors');
+const express = require('express');
+const path = require('path');
+const cookieParser = require('cookie-parser');
+const logger = require('morgan');
 
-let indexRouter = require('./routes/index');
+const indexRouter = require('./routes/index');
 
-let app = express();
+const app = express();
 
 // view engine setup
 app.set('views', path.join(__dirname, 'views'));
@@ -21,19 +21,8 @@ app.use(express.static(path.join(__dirname, 'public')));
 app.use('/', indexRouter);
 
 // catch 404 and forward to error handler
-app.use(function(req, res, next) {
+app.use(function (req, res, next) {
   next(createError(404));
 });
 
-// error handler
-app.use(function(err, req, res, next) {
-  // set locals, only providing error in development
-  res.locals.message = err.message;
-  res.locals.error = req.app.get('env') === 'development' ? err : {};
-
-  // render the error page
-  res.status(err.status || 500);
-  res.render('error');
-});
-
 module.exports = app;