Unable to find reference

[0x8f701]

trafficstars

    function _delegateToPool(
        DataTypes.ExecuteMarketplaceParams memory params,
        MarketplaceLocalVars memory vars
    ) internal returns (uint256, uint256) {
        uint256 price = vars.price;
        uint256 downpayment = price - vars.creditAmountInListingToken;
        if (!vars.isListingTokenETH) {
            address transferToken = vars.isListingTokenPToken
                ? vars.listingXTokenAddress
                : vars.listingToken;
            IERC20(transferToken).safeTransferFrom(
                params.orderInfo.taker,
                address(this),
                downpayment
            );
            Helpers.checkAllowance(transferToken, params.marketplace.operator);
            // convert to (priceEth, downpaymentEth)
            price = 0;
            downpayment = 0;
        } else {
            require(params.ethLeft >= downpayment, Errors.PAYNOW_NOT_ENOUGH);
        }

        return (price, downpayment);
    }

hardhat-vscode cannot find transferToken's reference