https://travis-ci.org/github/bitcoin/bitcoin/jobs/680452476#L6107
std::vector<bilingual_str> errors;
    CAmount old_fee;
    CAmount new_fee;
    CMutableTransaction mtx;
    feebumper::Result res;
    
    res = feebumper::CreateRateBumpTransaction(*pwallet, hash, coin_control, errors, old_fee, new_fee, mtx);
    if (res != feebumper::Result::OK) {
        switch(res) {
            case feebumper::Result::INVALID_ADDRESS_OR_KEY:
                throw JSONRPCError(RPC_INVALID_ADDRESS_OR_KEY, errors[0].original);
                break;
            case feebumper::Result::INVALID_REQUEST:
                throw JSONRPCError(RPC_INVALID_REQUEST, errors[0].original);
                break;
            case feebumper::Result::INVALID_PARAMETER:
                throw JSONRPCError(RPC_INVALID_PARAMETER, errors[0].original);
                break;
            case feebumper::Result::WALLET_ERROR:
                throw JSONRPCError(RPC_WALLET_ERROR, errors[0].original);
                break;
            default:
                throw JSONRPCError(RPC_MISC_ERROR, errors[0].original);
                break;
        }
    }
    UniValue result(UniValue::VOBJ);
    
    
    if (!want_psbt) {