NewHTTPError initialices a new error with a HTTPError implementation.

ALREADY_EXISTS is a constant representing the error message for a resource that already exists.

INTERNAL_SERVER_ERROR_MESSAGE is a common message used when a internal server error is perfomed.

NOT_FOUND_ERROR_MESSAGE is a constant representing the error message for a resource not being found.

UNAUTHORIZED_ERROR_MESSAGE is a constant representing the error message for unauthorized access.

HTTPError represents a error to present to the client.