fix: integer underflow in buyer algorithm (#145)

Author: stubbornick

src/AuctionHouseBot.cpp

@@ -244,8 +244,11 @@ void AuctionHouseBot::Buy(Player* AHBplayer, AHBConfig* config, WorldSession* se
         LOG_INFO("module", "AHBot [{}]: Considering {} auctions per interval to bid on.", _id, config->GetBidsPerInterval());
     }
 
-    for (uint32 count = 1; count <= config->GetBidsPerInterval(); ++count)
-    {
+    for (
+        uint32 count = 1;
+        count <= config->GetBidsPerInterval() && !auctionsGuidsToConsider.empty();
+        ++count
+    ) {
         //
         // Choose a random auction from possible auctions
         //