Fix crash after executing ItemList.set_icon_scale

scene/gui/item_list.cpp

@@ -1550,6 +1550,7 @@ bool ItemList::get_allow_reselect() const {
 }
 
 void ItemList::set_icon_scale(real_t p_scale) {
+	ERR_FAIL_COND(!Math::is_finite(p_scale));
 	icon_scale = p_scale;
 }