error.js

function error(err, options) {
  var originalError = null;
  if (typeof err.message === 'string' && err.message !== '') {
    if (typeof options === 'string' || (options && options.message)) {
      originalError = util.copy(err);
      originalError.message = err.message;
    }
  }
  err.message = err.message || null;

  if (typeof options === 'string') {
    err.message = options;
  } else if (typeof options === 'object' && options !== null) {
    util.update(err, options);
    if (options.message)
      err.message = options.message;
    if (options.code || options.name)
      err.code = options.code || options.name;
    if (options.stack)
      err.stack = options.stack;
  }

  if (typeof Object.defineProperty === 'function') {
    Object.defineProperty(err, 'name', {
      writable: true,
      enumerable: false
    });
    Object.defineProperty(err, 'message', {
      enumerable: true
    });
  }

  err.name = options && options.name || err.name || err.code || 'Error';
  err.time = new Date();

  if (originalError) err.originalError = originalError;

  return err;
}