Use more idiomatic sum method when possible

Author: tankyleo

lightning/src/chain/channelmonitor.rs

@@ -2863,8 +2863,7 @@ impl<Signer: EcdsaChannelSigner> ChannelMonitor<Signer> {
 				// In addition to `commit_tx_fee_sat`, this can also include dust HTLCs, and the total msat amount rounded down from non-dust HTLCs
 				transaction_fee_satoshis: if us.holder_pays_commitment_tx_fee.unwrap_or(true) {
 					let transaction = &us.funding.current_holder_commitment_tx.trust().built_transaction().transaction;
-					// Unwrap here; commitment transactions always have at least one output
-					let output_value_sat = transaction.output.iter().map(|txout| txout.value).reduce(|sum, value| sum + value).unwrap().to_sat();
+					let output_value_sat: u64 = transaction.output.iter().map(|txout| txout.value.to_sat()).sum();
 					us.funding.channel_parameters.channel_value_satoshis - output_value_sat
 				} else { 0 },
 				outbound_payment_htlc_rounded_msat,

lightning/src/ln/channel.rs

@@ -4140,12 +4140,17 @@ where
 		// Channel state once they will not be present in the next received commitment
 		// transaction).
 		let (local_balance_before_fee_msat, remote_balance_before_fee_msat) = {
-			let mut removed_outbound_total_msat = 0;
-			for htlc in self.pending_outbound_htlcs.iter() {
-				if let OutboundHTLCState::AwaitingRemoteRevokeToRemove(OutboundHTLCOutcome::Success(_, _)) | OutboundHTLCState::AwaitingRemovedRemoteRevoke(OutboundHTLCOutcome::Success(_, _)) = htlc.state {
-					removed_outbound_total_msat += htlc.amount_msat;
-				}
-			}
+			let removed_outbound_total_msat: u64 = self.pending_outbound_htlcs
+				.iter()
+				.filter_map(|htlc| {
+					matches!(
+						htlc.state,
+						OutboundHTLCState::AwaitingRemoteRevokeToRemove(OutboundHTLCOutcome::Success(_, _))
+						| OutboundHTLCState::AwaitingRemovedRemoteRevoke(OutboundHTLCOutcome::Success(_, _))
+					)
+					.then_some(htlc.amount_msat)
+				})
+				.sum();
 			let pending_value_to_self_msat =
 				funding.value_to_self_msat + htlc_stats.pending_inbound_htlcs_value_msat - removed_outbound_total_msat;
 			let pending_remote_value_msat =
@@ -4372,13 +4377,17 @@ where
 		}
 
 		if !funding.is_outbound() {
-			let mut removed_outbound_total_msat = 0;
-			for htlc in self.pending_outbound_htlcs.iter() {
-				if let OutboundHTLCState::AwaitingRemoteRevokeToRemove(OutboundHTLCOutcome::Success(_, _)) | OutboundHTLCState::AwaitingRemovedRemoteRevoke(OutboundHTLCOutcome::Success(_, _)) = htlc.state {
-					removed_outbound_total_msat += htlc.amount_msat;
-				}
-			}
-
+			let removed_outbound_total_msat: u64 = self.pending_outbound_htlcs
+				.iter()
+				.filter_map(|htlc| {
+					matches!(
+						htlc.state,
+						OutboundHTLCState::AwaitingRemoteRevokeToRemove(OutboundHTLCOutcome::Success(_, _))
+						| OutboundHTLCState::AwaitingRemovedRemoteRevoke(OutboundHTLCOutcome::Success(_, _))
+					)
+					.then_some(htlc.amount_msat)
+				})
+				.sum();
 			let pending_value_to_self_msat =
 				funding.value_to_self_msat + htlc_stats.pending_inbound_htlcs_value_msat - removed_outbound_total_msat;
 			let pending_remote_value_msat =