This probably is not a stinger, but an more automated anti-air system. S-200 maybe? The IFF addition to the stinger seems very modern. Did they sell such things to Iran during the Iran-contra days? The technology of Iran is not very advanced in certain directions. They even had a stealth aircraft that was a fake, 10 years ago.

They were expecting stealth aircraft. And these can only be hit with mostly automatic systems. The US and Israel were using "Friend" signatures in previous attacks on Iranian targets just days ago. This means that this fundamental identification could not be relied on. The radar signatures of modern attack aircraft can also mimic other aircraft (ECM/ECCCM). This may also be the reason the system could not identify accurately. In Yugoslavia they needed special modifications to the S-200 to hit the first stealth.

It would be interesting to see which weapon and identification system it is exactly. How it was configured and how well the operators were trained with this weapon. Even if these operators (and commander) were wanting to kill anything, I don't expect them to attack a friendly target willingly, as it is against their religion. It still means something to them. This would be different if the airplane was from Israel or US.

And knowing the CIA/Israel and how badly they want a war with Iran, it could even be a cyber-hack or an agent that caused the weapon to fire. In an attempt to start a war via the victims.

But I suspect that a human operator was at fault. Scared of an US attack and not trained well with the weapon, he pressed the button when the machine found a possible target. And this operator is now afraid of a possible execution.