Core/Items: Fix money refund amount. Also fix a possible exploit possibility of redeeming both vendor sellprice and money refund price in one go.

src/server/game/Entities/Player/Player.cpp

@@ -24424,14 +24424,16 @@ void Player::RefundItem(Item *item)
     data << uint32(iece->reqarenapoints);               // arena point cost
     for (uint8 i = 0; i < MAX_ITEM_EXTENDED_COST_REQUIREMENTS; ++i) // item cost data
     {
-        data << iece->reqitem[i];
-        data << (iece->reqitemcount[i]);
+        data << uint32(iece->reqitem[i]);
+        data << uint32(iece->reqitemcount[i]);
     }
     GetSession()->SendPacket(&data);
 
     // Delete any references to the refund data
     item->SetNotRefundable(this);
 
+    uint32 moneyRefund = item->GetPaidMoney();  // item-> will be invalidated in DestroyItem
+
     // Destroy item
     DestroyItem(item->GetBagSlot(), item->GetSlot(), true);
 
@@ -24451,7 +24453,7 @@ void Player::RefundItem(Item *item)
     }
 
     // Grant back money
-    if (uint32 moneyRefund = item->GetPaidMoney())
+    if (moneyRefund)
         ModifyMoney(moneyRefund);
 
     // Grant back Honor points

src/server/game/Server/Protocol/Handlers/ItemHandler.cpp

@@ -529,6 +529,12 @@ void WorldSession::HandleSellItemOpcode(WorldPacket & recv_data)
             return;
         }
 
+        // prevent selling item for sellprice when the item is still refundable
+        // this probably happens when right clicking a refundable item, the client sends both
+        // CMSG_SELL_ITEM and CMSG_REFUND_ITEM (unverified)
+        if (pItem->HasFlag(ITEM_FIELD_FLAGS, ITEM_FLAG_REFUNDABLE))
+            return; // Therefore, no feedback to client
+
         // special case at auto sell (sell all)
         if (count == 0)
         {