dealWithErrors.kt

sealed class Result<out T>{
    data class Ok<out T>(val value: T): Result<T>()
    data class Error(val description: String): Result<Nothing>()
}

data class BuyCryptoInfo(
  val username: String,
  val phoneNumber: PhoneNumber,
  val creditCard: CreditCard,
  val kycVerification: KycVerificationData){

  companion object{
      fun from1(user: CryptoUser): Result<BuyCryptoInfo> = with(user){
          if(phoneNumber == null) return Result.Error("missing phone number")
          if(creditCard == null) return Result.Error("missing credit card")
          if(kycVerification == null) return Result.Error("missing kyc verification")
          
          return Result.Ok(BuyCryptoInfo(username, phoneNumber, creditCard, kycVerification))
      }
  }  
}