Things should never "go wrong" with harvesting firewood or any chainsaw use. Pro loggers AND those of us who simply harvest our yearly firewood have done it for decades without any serious accidents.
Planning the felling with care, with intelligence. Often where we harvest there is no cell service. Most do NOT want anyone near a cutting.
Diligent planning of each cut includes looking up for those widows, making the hinge, clearing an escape route, knowing where and how the tree will (will) drop, and the use of tools such as wedges and skill to use bore cutting for safety to direct the fall.
This is not high end theoretical physics; just plain brains with experience. Many here boast about NOT using full PPE.
What?
Sorry . . . I know personally of at least one guy who was killed by a falling tree who may not have been a pro, but had been cutting firewood and pulp wood for years.
The guy was not a dumb guy . . . things sometimes do go wrong . . . whether planned or unplanned.