Fixed crash with Firewall / Forcefield cast when there is dead stack.

client/BattleInterface/CBattleInterface.cpp

@@ -2925,7 +2925,7 @@ void CBattleInterface::handleHex(BattleHex myNumber, int eventType)
 					auto tilesThatMustBeClear = sp->rangeInHexes(myNumber, hero->getSpellSchoolLevel(sp), side, &hexesOutsideBattlefield);
 					BOOST_FOREACH(BattleHex hex, tilesThatMustBeClear)
 					{
-						if(curInt->cb->battleGetStackByPos(hex)  ||  !!curInt->cb->battleGetObstacleOnPos(hex, false) 
+						if(curInt->cb->battleGetStackByPos(hex, false)  ||  !!curInt->cb->battleGetObstacleOnPos(hex, false) 
 						 || !hex.isAvailable())
 						{
 							legalAction = false;