These cases pop up from time to time and there have been at least 4 cases of death from earbud electrocution. The latest case was in the news a few days ago.
Seems most of them happened when the smartphone was being charged at the same time. I do not think the charging itself was the reason but IF an electric "surge" happens when the phone is plugged in as are the earbuds, evidently the result can be deadly.
Don't get in the habit of having your ears and brain as a "conduit" to completing a circuit to the AC line being hit by a surge.
