title: Winston is not writing logs to files
body: <p>I made two transports for errors and warnings in Winston that supposedly writes to files. The existing transport for console logging works fine, and I did check <code>pm2 logs</code> and saw the logs, but the transports for files are not saving anyting.</p>
  
  <pre><code>'use strict';
  
  const winston = require('winston');
  const m = require('moment-timezone');
  let logger = null;
  /**
   * Initializes the logger
   * @param {object} configLogging
   */
  module.exports.initialize = function initialize(configLogging) {
    const dateFormat = 'dddd, MMMM Do YYYY, h:mm:ss a';
  
    logger = new winston.Logger({
      transports: [
        new (winston.transports.Console)({
          name: 'info-console',
          level: configLogging.level,
          colorize: true,
          timestamp: function() { return m.utc().format(dateFormat); }
        }),
        new (winston.transports.File)({
          name: 'warning-file',
          filename: 'warning-file.log',
          level: 'warning'
        }),
        new (winston.transports.File)({
          name: 'error-file',
          filename: 'error-file.log',
          level: 'error'
        })
      ]
    });
  
    logger.info('Starting logging service');
  };
  
  /**
   * Gets the logger instance
   * @returns {LoggerInstance} winLogger
   */
  module.exports.get = function get() {
    return logger;
  };
  </code></pre>