Fix a few compilation warnings

Source/DiabloUI/settingsmenu.cpp

@@ -320,7 +320,7 @@ void FullscreenChanged()
 
 	for (auto &vecItem : vecDialogItems) {
 		int vecItemValue = vecItem->m_value;
-		if (vecItemValue < 0 || vecItemValue >= vecOptions.size())
+		if (vecItemValue < 0 || static_cast<size_t>(vecItemValue) >= vecOptions.size())
 			continue;
 
 		auto *pOption = vecOptions[vecItemValue];

Source/missiles.cpp

@@ -2304,8 +2304,6 @@ void AddStoneCurse(Missile &missile, AddMissileParameter &parameter)
 	missile.var2 = monsterId;
 	monster.petrify();
 
-	Player &player = Players[missile._misource];
-
 	// And set up the missile to unpetrify it in the future
 	missile.position.tile = *targetMonsterPosition;
 	missile.position.start = missile.position.tile;
@@ -2448,8 +2446,6 @@ void AddFireWallControl(Missile &missile, AddMissileParameter &parameter)
 
 void AddInfravision(Missile &missile, AddMissileParameter & /*parameter*/)
 {
-	Player &player = Players[missile._misource];
-
 	missile._mirange = ScaleSpellEffect(1584, missile._mispllvl);
 }
 

Source/monster.cpp

@@ -4707,7 +4707,7 @@ MonsterMode Monster::getVisualMonsterMode() const
 	size_t monsterId = this->getId();
 	for (auto &missile : Missiles) {
 		// Search the missile that will restore the original monster mode and use the saved/original monster mode from it
-		if (missile._mitype == MissileID::StoneCurse && missile.var2 == monsterId) {
+		if (missile._mitype == MissileID::StoneCurse && static_cast<size_t>(missile.var2) == monsterId) {
 			return static_cast<MonsterMode>(missile.var1);
 		}
 	}