Errors.js

/**
 * @param {string} name
 * @param {string} defaultMessage
 * @returns {Function}
 * @private
 */
function createError(name, defaultMessage) {
  function NewError(message) {
    this.name = name;
    this.message = message || defaultMessage;
    this.stack = (new Error()).stack;
  }

  NewError.prototype = Object.create(Error.prototype);
  NewError.prototype.constructor = NewError;

  return NewError;
}

var errors = module.exports = {
  FileSystemError: createError('FileSystemError', 'error in FileSystem call')
};