Swift6 handle error, Typed Throws sample code

enum ValidationError: Error {
     case invalidInput
     case missingInput
     case alreadyInUse
}

extension ValidationError: LocalizedError {
    var errorDescription: String? {
    switch self {
    case .invalidInput:
        return "xxxxx"
    case .missingInput:
        return "The username cannot be empty"
    case .alreadyInUse:
        return "This username is already in use. Please try again"
    }
}

class InputValidator {
    func validateWithTypedThrow(_ input: String) throws(ValidationError) {
        guard !input.isEmpty else { throw .missingInput }
        guard input.count > 2 else { throw .invalidInput }
        guard !existingUsernames.contains(input) else { throw .alreadyInUse }
    }
}


// Event
Button("Validate") {
    do throws(ValidationError) {
        try validator.validateWithTypedThrow(username)
        self.errorMessage = nil
        self.successMessage = "Validation successful!"
    } catch {
        self.errorMessage = error.localizaedDescription

        switch error {
        case .invalidInput:
            break // do something ex) call api
        case .missingInput:
            break // present alert
        case .alreadyInUse:
            break // do something
        }
    } /* catch let error as ValidationError {
    
    } */
}