btcpayserver/BTCPayServer/Services/Rates/RateUnavailableException.cs

using System;
using System.Collections.Generic;
using System.Text;

namespace BTCPayServer.Services.Rates
{
    public class RateUnavailableException : Exception
    {
        public RateUnavailableException(string currency) : base("Rate unavailable for currency " + currency)
        {
            if (currency == null)
                throw new ArgumentNullException(nameof(currency));
            Currency = currency;
        }

        public string Currency
        {
            get; set;
        }
    }
}