Modified again to use Handlebars template instead of Jade

ErrorHandler.js

/**
 * Modified from the Connect project: https://github.com/senchalabs/connect/blob/master/lib/middleware/errorHandler.js
 *
 * Flexible error handler, providing (_optional_) stack traces and logging
 * and error message responses for requests accepting text, html, or json.
 *
 * Options:
 *
 *   - `showStack` respond with both the error message and stack trace. Defaults to `false`
 *   - `showMessage`, respond with the exception message only. Defaults to `false`
 *   - `dumpExceptions`, dump exceptions to stderr (without terminating the process). Defaults to `false`
 *   - `logErrors`, will dump a log entry and stack trace into the gievn file. Defaults to `false`
 *
 * Text:
 *   By default, and when _text/plain_ is accepted a simple stack trace
 *   or error message will be returned.
 *
 * JSON:
 *   When _application/json_ is accepted, connect will respond with
 *   an object in the form of `{ 'error': error }`. 
 *
 * HTML:
 *   When accepted connect will output a nice html stack trace.
 *
 * @param {Object} options
 * @return {Function}
 * @api public
 */

var fs = require('fs');

exports = module.exports = function errorHandler (options) {
  options             = options || {};
  
  // defaults
  var showStack       = options.showStack;
  var showMessage     = options.showMessage;
  var dumpExceptions  = options.dumpExceptions;
  var logErrors       = options.logErrors;
  var logErrorsStream = false;
  
  if (options.logErrors) {
    logErrorsStream = fs.createWriteStream(logErrors, { 'flags': 'a', encoding: 'utf-8', mode: 0666 });
  }

  return function errorHandler (err, req, res, next) {
    res.statusCode = 500;

    if (dumpExceptions) {
      console.error(err.stack);
    }

    if (logErrors) {
      var now = new Date();
      logErrorsStream.write(now.toJSON() + ' - Error Happened: \n' + err.stack + '\n');
    }

    var accept = req.headers.accept || '';
    
    if (showStack) {
      if (~accept.indexOf('html')) {
        // html
        res.render('error', {
          stack: err.stack || '',
          error: err.toString() 
        });
      }
      else if (~accept.indexOf('json')) {
        // json
        var json = JSON.stringify({ error: err });
        res.setHeader('Content-Type', 'application/json');
        res.end(json);
      }
      else {
        // plain text
        res.writeHead(500, { 'Content-Type': 'text/plain' });
        res.end(err.stack);
      }
    } else {
      // public error page render
      if (~accept.indexOf('html')) {
        // html
        res.render('error');
      }
      else if (~accept.indexOf('json')) {
        // json
        var json = JSON.stringify({ error: 'There was a server error generating the content.' });
        res.setHeader('Content-Type', 'application/json');
        res.end(json);
      }
      else {
        // plain text
        res.writeHead(500, { 'Content-Type': 'text/plain' });
        res.end('500 - Server Error');
      }
    }
  };
};