Pass taskPrice instead of dealPrice to refund function

contracts/beacon/Voucher.sol

@@ -200,9 +200,9 @@ contract Voucher is OwnableUpgradeable, IVoucher {
                 voucherHub,
                 iexecPoco,
                 taskId,
+                deal.app.price + deal.dataset.price + deal.workerpool.price, // taskPrice
                 task.dealid,
                 deal.botSize,
-                (deal.app.price + deal.dataset.price + deal.workerpool.price) * deal.botSize,
                 deal.requester
             );
         }
@@ -233,9 +233,9 @@ contract Voucher is OwnableUpgradeable, IVoucher {
                 voucherHub,
                 iexecPoco,
                 taskId,
+                deal.appPrice + deal.datasetPrice + deal.workerpoolPrice, // taskPrice
                 dealId,
                 deal.botSize,
-                (deal.appPrice + deal.datasetPrice + deal.workerpoolPrice) * deal.botSize,
                 deal.requester
             );
         }
@@ -312,27 +312,25 @@ contract Voucher is OwnableUpgradeable, IVoucher {
      * @param voucherHub hub
      * @param iexecPoco address of PoCo contract
      * @param taskId id of the task
+     * @param taskPrice price paid per task at match orders
      * @param dealId task's deal id
      * @param dealVolume number of tasks in the deal
-     * @param dealPrice price paid at match orders
      * @param requester of the task
      */
     function _refundVoucherAndRequester(
         IVoucherHub voucherHub,
         address iexecPoco,
         bytes32 taskId,
+        uint256 taskPrice,
         bytes32 dealId,
         uint256 dealVolume,
-        uint256 dealPrice,
         address requester
     ) private {
         VoucherStorage storage $ = _getVoucherStorage();
-        require(!$._refundedTasks[taskId], "Voucher: task already claimed");
+        require(!$._refundedTasks[taskId], "Voucher: task already refunded");
         $._refundedTasks[taskId] = true;
-        if (dealPrice != 0) {
+        if (taskPrice != 0) {
             uint256 dealSponsoredAmount = $._sponsoredAmounts[dealId];
-            // The division yields no remainder since dealPrice = taskPrice * volume.
-            uint256 taskPrice = dealPrice / dealVolume;
             // A positive remainder is possible when the voucher balance is less than
             // the sponsorable amount. Min(balance, dealSponsoredAmount) is computed
             // at match orders.