'Invalid username provided.', self::BAD_PASSWORD => 'Invalid password provided.', self::BAD_EMAIL => 'Invalid email address provided.', self::USERNAME_IN_USE => 'Username is already in use.', self::EMAIL_IN_USE => 'Email address is already in use.', self::BAD_INVITE_CODE => 'Invalid or expired invite code.', self::SUCCESS => 'Registration successful.', }; } public function isError(): bool { return $this->value < 0; } public function isSuccess(): bool { return $this === self::SUCCESS; } }