RPC bumpfee with an explicit feerate using `conf_target` and `estimate_mode` errors with `JSONRPCException: JSON integer out of range (-1)`.
{
    std::shared_ptr<CWallet> const wallet = GetWalletForJSONRPCRequest(request);
    if (!wallet) return NullUniValue;
    const CWallet* const pwallet = wallet.get();
    LOCK(pwallet->cs_wallet);
    std::vector<COutPoint> vOutpts;
    pwallet->ListLockedCoins(vOutpts);
    UniValue ret(UniValue::VARR);
    for (const COutPoint& outpt : vOutpts) {
        UniValue o(UniValue::VOBJ);
        o.pushKV("txid", outpt.hash.GetHex());
        o.pushKV("vout", (int)outpt.n);
        ret.push_back(o);
    }
    return ret;
},
    };
}
static RPCHelpMan settxfee()
{
    return RPCHelpMan{"settxfee",
                "\nSet the transaction fee per kB for this wallet. Overrides the global -paytxfee command line parameter.\n"
                "Can be deactivated by passing 0 as the fee. In that case automatic fee selection will be used by default.\n",
                {
                    {"amount", RPCArg::Type::AMOUNT, RPCArg::Optional::NO, "The transaction fee in " + CURRENCY_UNIT + "/kB"},
                },
                RPCResult{
                    RPCResult::Type::BOOL, "", "Returns true if successful"
                },
                RPCExamples{