Core/AuctionHouse: Fixed possible use after free when auctions are removed with offline buyers

Port From (https://github.com/TrinityCore/TrinityCore/commit/1f73cf9f19679f5b888f9df475b94c9405f2d746)

Source/Game/AuctionHouse/AuctionManager.cs

@@ -785,20 +785,25 @@ namespace Game
                 {
                     SendAuctionExpired(auction, trans);
                     Global.ScriptMgr.OnAuctionExpire(this, auction);
+
+                    RemoveAuction(trans, auction);
                 }
                 ///- Or perform the transaction
                 else
                 {
+                    // Copy data before freeing AuctionPosting in auctionHouse->RemoveAuction
+                    // Because auctionHouse->SendAuctionWon can unload items if bidder is offline
+                    // we need to RemoveAuction before sending mails
+                    AuctionPosting copy = auction;
+                    RemoveAuction(trans, auction);
+
                     //we should send an "item sold" message if the seller is online
                     //we send the item to the winner
                     //we send the money to the seller
-                    SendAuctionWon(auction, null, trans);
+                    SendAuctionSold(copy, null, trans);
-                    SendAuctionSold(auction, null, trans);
+                    SendAuctionWon(copy, null, trans);
                     Global.ScriptMgr.OnAuctionSuccessful(this, auction);
                 }
-
-                ///- In any case clear the auction
-                RemoveAuction(trans, auction);
             }
 
             // Run DB changes

Source/Game/Handlers/AuctionHandler.cs

@@ -390,8 +390,8 @@ namespace Game
             if (canBuyout && placeBid.BidAmount == auction.BuyoutOrUnitPrice)
             {
                 // buyout
-                auctionHouse.SendAuctionWon(auction, player, trans);
                 auctionHouse.SendAuctionSold(auction, null, trans);
+                auctionHouse.SendAuctionWon(auction, player, trans);
 
                 auctionHouse.RemoveAuction(trans, auction);
             }