It’s a force close. Could be due to HTLC on expire, could be one side publishing an old state. It’s often automated by the node software, and not a conscious human actions. It happens. State gets corrupt, node tears down a channel to restore a known state. I have had several, out of my control, costing me lots of sats :-(

This all demonstrates the lack of sustainability of Lightning. The bleeding of sats will continue until the spam goes away. The fact some morons can break Lightning for $60 worth of jpegs shows you this tech isn’t working as expected