f clarify error messages

Author: TheBlueMatt

lightning/src/chain/channelmonitor.rs

@@ -114,7 +114,7 @@ impl Readable for ChannelMonitorUpdate {
 }
 
 /// An error enum representing a failure to persist a channel monitor update.
-#[derive(Clone, Debug)]
+#[derive(Clone, Copy, Debug, PartialEq)]
 pub enum ChannelMonitorUpdateErr {
 	/// Used to indicate a temporary failure (eg connection to a watchtower or remote backup of
 	/// our state failed, but is expected to succeed at some point in the future).

lightning/src/ln/channelmanager.rs

@@ -57,7 +57,7 @@ use util::events::{EventHandler, EventsProvider, MessageSendEvent, MessageSendEv
 use util::{byte_utils, events};
 use util::ser::{Readable, ReadableArgs, MaybeReadable, Writeable, Writer};
 use util::chacha20::{ChaCha20, ChaChaReader};
-use util::logger::Logger;
+use util::logger::{Logger, Level};
 use util::errors::APIError;
 
 use prelude::*;
@@ -2683,6 +2683,9 @@ impl<Signer: Sign, M: Deref, T: Deref, K: Deref, F: Deref, L: Deref> ChannelMana
 				Ok(msgs_monitor_option) => {
 					if let UpdateFulfillCommitFetch::NewClaim { msgs, monitor_update } = msgs_monitor_option {
 						if let Err(e) = self.chain_monitor.update_channel(chan.get().get_funding_txo().unwrap(), monitor_update) {
+							log_given_level!(self.logger, if e == ChannelMonitorUpdateErr::PermanentFailure { Level::Error } else { Level::Debug },
+								"Failed to update channel monitor with preimage {:?}: {:?}",
+								payment_preimage, e);
 							return Err(Some((
 								chan.get().get_counterparty_node_id(),
 								handle_monitor_err!(self, e, channel_state, chan, RAACommitmentOrder::CommitmentFirst, false, msgs.is_some()).unwrap_err(),
@@ -2708,7 +2711,8 @@ impl<Signer: Sign, M: Deref, T: Deref, K: Deref, F: Deref, L: Deref> ChannelMana
 				},
 				Err((e, monitor_update)) => {
 					if let Err(e) = self.chain_monitor.update_channel(chan.get().get_funding_txo().unwrap(), monitor_update) {
-						log_error!(self.logger, "Critical error: failed to update channel monitor with preimage {:?}: {:?}",
+						log_given_level!(self.logger, if e == ChannelMonitorUpdateErr::PermanentFailure { Level::Error } else { Level::Info },
+							"Failed to update channel monitor with preimage {:?} immediately prior to force-close: {:?}",
 							payment_preimage, e);
 					}
 					let counterparty_node_id = chan.get().get_counterparty_node_id();