Does "fail the channel" mean unilateral close in BOLTS? The BOLTs frequently mentioned &quot;fail the channel&quot; when something unexpected is received or happens. For instance, when receiving an update_fulfill_htlc message, you should fail the channel if the received channel ID isn't known.
At this point, you would have money stuck in a channel, so does this mean you should try to close unilaterally, cooperatively, either? Is &quot;fail the channel&quot; defined in the bolts somewhere?
And it's in BOLT #5 Failing a Channel