NKAI: fix crash

AI/Nullkiller/Analyzers/ArmyManager.cpp

@@ -182,8 +182,10 @@ std::vector<SlotInfo> ArmyManager::getBestArmy(const IBonusBearer * armyCarrier,
 	{
 		auto weakest = getWeakestCreature(resultingArmy);
 
-		if(weakest != resultingArmy.end() && weakest->count == 1) //we check iterator validity for playing with settings that allow 0 stacks armies
+		if(weakest->count == 1) 
 		{
+			assert(resultingArmy.size() > 1);
+
 			resultingArmy.erase(weakest);
 		}
 		else

AI/Nullkiller/Behaviors/GatherArmyBehavior.cpp

@@ -250,10 +250,13 @@ Goals::TGoalVec GatherArmyBehavior::upgradeArmy(const CGTownInstance * upgrader)
 
 		auto upgrade = ai->nullkiller->armyManager->calculateCreaturesUpgrade(path.heroArmy, upgrader, availableResources);
 
-		if(ai->nullkiller->heroManager->getHeroRole(path.targetHero) == HeroRole::MAIN)
+		if(!upgrader->garrisonHero && ai->nullkiller->heroManager->getHeroRole(path.targetHero) == HeroRole::MAIN)
 		{
 			upgrade.upgradeValue +=	
-				ai->nullkiller->armyManager->howManyReinforcementsCanGet(path.targetHero, path.heroArmy, upgrader);	
+				ai->nullkiller->armyManager->howManyReinforcementsCanGet(
+					path.targetHero,
+					path.heroArmy,
+					upgrader->getUpperArmy());	
 		}
 
 		auto armyValue = (float)upgrade.upgradeValue / path.getHeroStrength();

AI/Nullkiller/Pathfinding/Actors.cpp

@@ -274,12 +274,12 @@ ExchangeResult HeroExchangeMap::tryExchangeNoLock(const ChainActor * other)
 			return result;
 		}
 
-	if(other->isMovable && other->armyValue <= actor->armyValue / 10 && other->armyValue < MIN_ARMY_STRENGTH_FOR_CHAIN)
-		return result;
+		if(other->isMovable && other->armyValue <= actor->armyValue / 10 && other->armyValue < MIN_ARMY_STRENGTH_FOR_CHAIN)
+			return result;
 
-	TResources availableResources = resources - actor->armyCost - other->armyCost;
-	HeroExchangeArmy * upgradedInitialArmy = tryUpgrade(actor->creatureSet, other->getActorObject(), availableResources);
-	HeroExchangeArmy * newArmy;
+		TResources availableResources = resources - actor->armyCost - other->armyCost;
+		HeroExchangeArmy * upgradedInitialArmy = tryUpgrade(actor->creatureSet, other->getActorObject(), availableResources);
+		HeroExchangeArmy * newArmy;
 
 		if(other->creatureSet->Slots().size())
 		{
@@ -303,20 +303,25 @@ ExchangeResult HeroExchangeMap::tryExchangeNoLock(const ChainActor * other)
 
 		if(!newArmy) return result;
 
-		auto reinforcement = newArmy->getArmyStrength() - actor->creatureSet->getArmyStrength();
+		auto newArmyStrength = newArmy->getArmyStrength();
+		auto oldArmyStrength = actor->creatureSet->getArmyStrength();
 
-#if NKAI_PATHFINDER_TRACE_LEVEL >= 2
+		if(newArmyStrength <= oldArmyStrength) return result;
+
+		auto reinforcement = newArmyStrength - oldArmyStrength;
+
+	#if NKAI_PATHFINDER_TRACE_LEVEL >= 2
 		logAi->trace(
 			"Exchange %s->%s reinforcement: %d, %f%%",
 			actor->toString(),
 			other->toString(),
 			reinforcement,
 			100.0f * reinforcement / actor->armyValue);
-#endif
+	#endif
 
-	if(reinforcement <= actor->armyValue / 10 && reinforcement < MIN_ARMY_STRENGTH_FOR_CHAIN)
-	{
-		delete newArmy;
+		if(reinforcement <= actor->armyValue / 10 && reinforcement < MIN_ARMY_STRENGTH_FOR_CHAIN)
+		{
+			delete newArmy;
 
 			return result;
 		}
@@ -365,7 +370,7 @@ HeroExchangeArmy * HeroExchangeMap::tryUpgrade(
 	{
 		auto buyArmy = ai->armyManager->getArmyAvailableToBuy(target, ai->cb->getTown(upgrader->id), resources);
 
-		for(auto creatureToBuy : buyArmy)
+		for(auto & creatureToBuy : buyArmy)
 		{
 			auto targetSlot = target->getSlotFor(creatureToBuy.cre);