This is a little bit silly, that pretty clearly was a mistake, it also led to new ROE regarding the safety cordon around approved targets. Additionally Serbia was a combatant nation, that's why embassies often evacuate nations involved in hostilities. Israel routinely attacks 3rd country targets, they struck with multiple weapons. Syria and Iraq are not parties to the current situation in Gaza. The idea that countries with governments or general population that are not in favour of the IDF massacre of civilians means almost every country is "involved" according to Israeli targeting doctrine.