Is expiation obligatory for one who swears an oath about something he believes to be true, only for it to later turn out otherwise, or for one who swears an oath about a future event that has not occurred, while intending to swear a truthful, not a false, oath?

If a person swears an oath on something they believe to be true, and it later turns out to be otherwise, their oath is considered a "laghw" (unintentional oath) and no expiation is required for it, as stated in the verse: (Allah will not impose blame upon you for what is unintentional in your oaths, but He will impose blame upon you for what your hearts have earned.) [Al-Baqarah: 225]. It was narrated from Aisha, may Allah be pleased with her, that unintentional oaths are those made during arguing, jesting, or playing. Most scholars hold the view that no expiation is due for such an oath.