chanmon_consistency: skip channels without SCID in MPP sends

send_mpp_payment and send_mpp_hop_payment used list_channels()
and unwrapped short_channel_id, which panics for channels that
have been force-closed or are not yet fully open. Filter out
channels without an SCID and send over the remaining ones,
recomputing path count and amounts accordingly.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: joostjager

fuzz/src/chanmon_consistency.rs

@@ -713,24 +713,25 @@ fn send_mpp_payment(
 	source: &ChanMan, dest: &ChanMan, dest_chan_ids: &[ChannelId], amt: u64,
 	payment_secret: PaymentSecret, payment_hash: PaymentHash, payment_id: PaymentId,
 ) -> bool {
-	let num_paths = dest_chan_ids.len();
+	let mut paths = Vec::new();
+
+	let dest_chans = dest.list_channels();
+	let dest_scids: Vec<_> = dest_chan_ids
+		.iter()
+		.filter_map(|chan_id| {
+			dest_chans
+				.iter()
+				.find(|chan| chan.channel_id == *chan_id)
+				.and_then(|chan| chan.short_channel_id)
+		})
+		.collect();
+	let num_paths = dest_scids.len();
 	if num_paths == 0 {
 		return false;
 	}
-
 	let amt_per_path = amt / num_paths as u64;
-	let mut paths = Vec::with_capacity(num_paths);
-
-	let dest_chans = dest.list_channels();
-	let dest_scids = dest_chan_ids.iter().map(|chan_id| {
-		dest_chans
-			.iter()
-			.find(|chan| chan.channel_id == *chan_id)
-			.and_then(|chan| chan.short_channel_id)
-			.unwrap()
-	});
 
-	for (i, dest_scid) in dest_scids.enumerate() {
+	for (i, dest_scid) in dest_scids.into_iter().enumerate() {
 		let path_amt = if i == num_paths - 1 {
 			amt - amt_per_path * (num_paths as u64 - 1)
 		} else {
@@ -772,41 +773,38 @@ fn send_mpp_hop_payment(
 	dest_chan_ids: &[ChannelId], amt: u64, payment_secret: PaymentSecret,
 	payment_hash: PaymentHash, payment_id: PaymentId,
 ) -> bool {
-	// Create paths by pairing middle_scids with dest_scids
-	let num_paths = middle_chan_ids.len().max(dest_chan_ids.len());
-	if num_paths == 0 {
-		return false;
-	}
-
-	let first_hop_fee = 50_000;
-	let amt_per_path = amt / num_paths as u64;
-	let fee_per_path = first_hop_fee / num_paths as u64;
-	let mut paths = Vec::with_capacity(num_paths);
-
 	let middle_chans = middle.list_channels();
 	let middle_scids: Vec<_> = middle_chan_ids
 		.iter()
-		.map(|chan_id| {
+		.filter_map(|chan_id| {
 			middle_chans
 				.iter()
 				.find(|chan| chan.channel_id == *chan_id)
 				.and_then(|chan| chan.short_channel_id)
-				.unwrap()
 		})
 		.collect();
 
 	let dest_chans = dest.list_channels();
 	let dest_scids: Vec<_> = dest_chan_ids
 		.iter()
-		.map(|chan_id| {
+		.filter_map(|chan_id| {
 			dest_chans
 				.iter()
 				.find(|chan| chan.channel_id == *chan_id)
 				.and_then(|chan| chan.short_channel_id)
-				.unwrap()
 		})
 		.collect();
 
+	let num_paths = middle_scids.len().max(dest_scids.len());
+	if middle_scids.is_empty() || dest_scids.is_empty() {
+		return false;
+	}
+
+	let first_hop_fee = 50_000;
+	let amt_per_path = amt / num_paths as u64;
+	let fee_per_path = first_hop_fee / num_paths as u64;
+	let mut paths = Vec::with_capacity(num_paths);
+
 	for i in 0..num_paths {
 		let middle_scid = middle_scids[i % middle_scids.len()];
 		let dest_scid = dest_scids[i % dest_scids.len()];