Drop ChannelMonitorUpdate::UpdateFailed as its now unused

Author: TheBlueMatt

lightning/src/chain/channelmonitor.rs

@@ -150,21 +150,15 @@ pub enum MonitorEvent {
 		/// same [`ChannelMonitor`] have been applied and persisted.
 		monitor_update_id: u64,
 	},
-
-	/// Indicates a [`ChannelMonitor`] update has failed.
-	UpdateFailed(OutPoint),
 }
 impl_writeable_tlv_based_enum_upgradable!(MonitorEvent,
-	// Note that Completed and UpdateFailed are currently never serialized to disk as they are
-	// generated only in ChainMonitor
 	(0, Completed) => {
 		(0, funding_txo, required),
 		(2, monitor_update_id, required),
 	},
 ;
 	(2, HTLCEvent),
 	(4, CommitmentTxConfirmed),
-	(6, UpdateFailed),
 );
 
 /// Simple structure sent back by `chain::Watch` when an HTLC from a forward channel is detected on

lightning/src/ln/channelmanager.rs

@@ -6518,8 +6518,7 @@ where
 							self.fail_htlc_backwards_internal(&htlc_update.source, &htlc_update.payment_hash, &reason, receiver);
 						}
 					},
-					MonitorEvent::CommitmentTxConfirmed(funding_outpoint) |
-					MonitorEvent::UpdateFailed(funding_outpoint) => {
+					MonitorEvent::CommitmentTxConfirmed(funding_outpoint) => {
 						let counterparty_node_id_opt = match counterparty_node_id {
 							Some(cp_id) => Some(cp_id),
 							None => {
@@ -6543,12 +6542,7 @@ where
 												msg: update
 											});
 										}
-										let reason = if let MonitorEvent::UpdateFailed(_) = monitor_event {
-											ClosureReason::ProcessingError { err: "Failed to persist ChannelMonitor update during chain sync".to_string() }
-										} else {
-											ClosureReason::CommitmentTxConfirmed
-										};
-										self.issue_channel_close_events(&chan.context, reason);
+										self.issue_channel_close_events(&chan.context, ClosureReason::CommitmentTxConfirmed);
 										pending_msg_events.push(events::MessageSendEvent::HandleError {
 											node_id: chan.context.get_counterparty_node_id(),
 											action: msgs::ErrorAction::SendErrorMessage {