Fixed possible crash if hero class has no valid commander ID

lib/CHeroHandler.cpp

@@ -218,8 +218,7 @@ void CHeroClass::serializeJson(JsonSerializeFormat & handler)
 CHeroClass::CHeroClass():
 	faction(0),
 	affinity(0),
-	defaultTavernChance(0),
-	commander(nullptr) 
+	defaultTavernChance(0)
 {
 }
 
@@ -302,7 +301,7 @@ CHeroClass * CHeroClassHandler::loadFromJson(const std::string & scope, const Js
 	VLC->identifiers()->requestIdentifier ("creature", node["commander"],
 	[=](si32 commanderID)
 	{
-		heroClass->commander = CreatureID(commanderID).toCreature();
+		heroClass->commander = CreatureID(commanderID);
 	});
 
 	heroClass->defaultTavernChance = static_cast<ui32>(node["defaultTavern"].Float());

lib/CHeroHandler.h

@@ -121,7 +121,7 @@ public:
 	// resulting chance = sqrt(town.chance * heroClass.chance)
 	ui32 defaultTavernChance;
 
-	const CCreature * commander;
+	CreatureID commander;
 
 	std::vector<int> primarySkillInitial;  // initial primary skills
 	std::vector<int> primarySkillLowLevel; // probability (%) of getting point of primary skill when getting level

lib/mapObjects/CGHeroInstance.cpp

@@ -402,9 +402,9 @@ void CGHeroInstance::initHero(CRandomGenerator & rand)
 		addNewBonus(bonus);
 	}
 
-	if (VLC->settings()->getBoolean(EGameSettings::MODULE_COMMANDERS) && !commander)
+	if (VLC->settings()->getBoolean(EGameSettings::MODULE_COMMANDERS) && !commander && type->heroClass->commander.hasValue())
 	{
-		commander = new CCommanderInstance(type->heroClass->commander->getId());
+		commander = new CCommanderInstance(type->heroClass->commander);
 		commander->setArmyObj (castToArmyObj()); //TODO: separate function for setting commanders
 		commander->giveStackExp (exp); //after our exp is set
 	}