@mbernal/nodejs-create-react-app/middleware/express/serverErrors.js

module.exports = function({app}){
    
  //Log all errors
  app.use(function (err, req, res, next) {
      if(err.statusCode!=401)
        console.error("Error", {status: err.statusCode, message: err.message, error: err});
      next(err);
  });
  
  // catch 404 and forward to error handler
  // app.use(function (req, res, next) {
  //     var err = new Error('Not Found');
  //     err.statusCode = 404;
  //     next(err);
  // });

  // error handlers
  
  // development error handler
  // will print stacktrace
  if (process.env.NODE_ENV === 'development') {
      app.use(function (err, req, res, next) {
          if(req.headers['content-type'] && req.headers['content-type'].indexOf("application/json")>=0){
              return res.status(err.status || err.statusCode || 500).send({statusCode:err.statusCode,message:err.message});
          }
          else(
              res.status(err.status || err.statusCode || 500).render('error', {
                  message: err.message,
                  error: err
              })
          )
      });
  }

  // production error handler
  // no stacktraces leaked to user
  app.use(function (err, req, res, next) {
      if(req.headers['content-type'] && req.headers['content-type'].indexOf("application/json")>=0){
          return res.status(err.status || err.statusCode || 500).send(err);
      }
      else(
          res.status(err.status || err.statusCode || 500).render('error', {
              message: err.message,
              error: {}
          })
      )
  });
}