I have some error classes defined like so;

class CustomError implements IError {...}
class UnauthorizedError extends CustomError {...}
class NotFoundError extends CustomError {...}
class BadRequestError extends CustomError {...}

and an enum Err defined as follow;

enum Err {
      unauthorized = "UnauthorizedError",
      custom = "CustomError",
      notFound = "NotFoundError",
      badRequest = "BadRequestError",
}

how can i turn Err.notFound for example into the class NotFoundError.