Continue after a single failure in ChannelMonitor::update_monitor

`ChannelMonitorUpdate`s may contain multiple updates, including, eg
a payment preimage after a commitment transaction update. While
such updates are generally not generated today, we shouldn't return
early out of the update loop, causing us to miss any updates after
an earlier update fails.

Author: TheBlueMatt

lightning/src/chain/channelmonitor.rs

@@ -1796,12 +1796,15 @@ impl<Signer: Sign> ChannelMonitorImpl<Signer> {
 		} else if self.latest_update_id + 1 != updates.update_id {
 			panic!("Attempted to apply ChannelMonitorUpdates out of order, check the update_id before passing an update to update_monitor!");
 		}
+		let mut ret = Ok(());
 		for update in updates.updates.iter() {
 			match update {
 				ChannelMonitorUpdateStep::LatestHolderCommitmentTXInfo { commitment_tx, htlc_outputs } => {
 					log_trace!(logger, "Updating ChannelMonitor with latest holder commitment transaction info");
 					if self.lockdown_from_offchain { panic!(); }
-					self.provide_latest_holder_commitment_tx(commitment_tx.clone(), htlc_outputs.clone())?
+					if let Err(e) = self.provide_latest_holder_commitment_tx(commitment_tx.clone(), htlc_outputs.clone()) {
+						ret = Err(e);
+					}
 				}
 				ChannelMonitorUpdateStep::LatestCounterpartyCommitmentTXInfo { commitment_txid, htlc_outputs, commitment_number, their_revocation_point } => {
 					log_trace!(logger, "Updating ChannelMonitor with latest counterparty commitment transaction info");
@@ -1813,7 +1816,9 @@ impl<Signer: Sign> ChannelMonitorImpl<Signer> {
 				},
 				ChannelMonitorUpdateStep::CommitmentSecret { idx, secret } => {
 					log_trace!(logger, "Updating ChannelMonitor with commitment secret");
-					self.provide_secret(*idx, *secret)?
+					if let Err(e) = self.provide_secret(*idx, *secret) {
+						ret = Err(e);
+					}
 				},
 				ChannelMonitorUpdateStep::ChannelForceClosed { should_broadcast } => {
 					log_trace!(logger, "Updating ChannelMonitor: channel force closed, should broadcast: {}", should_broadcast);
@@ -1838,7 +1843,7 @@ impl<Signer: Sign> ChannelMonitorImpl<Signer> {
 			}
 		}
 		self.latest_update_id = updates.update_id;
-		Ok(())
+		ret
 	}
 
 	pub fn get_latest_update_id(&self) -> u64 {