RPC bumpfee with an explicit feerate using `conf_target` and `estimate_mode` errors with `JSONRPCException: JSON integer out of range (-1)`.
{
    std::string res;
    res += "\"";
    res += GetFirstName();
    if (oneline) {
        res += "\":";
    } else {
        res += "\": ";
    }
    switch (m_type) {
    case Type::STR:
        return res + "\"str\"";
    case Type::STR_HEX:
        return res + "\"hex\"";
    case Type::NUM:
        return res + "n";
    case Type::RANGE:
        return res + "n or [n,n]";
    case Type::AMOUNT:
        return res + "amount";
    case Type::BOOL:
        return res + "bool";