code: function (cfg, state, n) {
          return function (err) {
              if (err.code == "ENOENT") {
                  logger.logError("Spawn: exited with code ENOENT. PhantomJS executable not found. Make sure to download PhantomJS and add its folder to your system's PATH, or pass the full path directly to Attester via --phantomjs-path.\nUsed command: '" + cfg.phantomPath + "'");
              } else {
                  logger.logError("Unable to spawn PhantomJS; error code " + err.code);
              }
          };
      }
docs: Factory of callback functions to be used as 'error' listener by PhantomJS processes.
  @param {Object} cfg
  @param {Object} state
  @param {Integer} n
  @return {Function}