fuzz: handle missing SendTx* message events in chanmon_consistency

Add handlers for SendTxInitRbf, SendTxAckRbf, SendTxRemoveInput, and
SendTxRemoveOutput in the chanmon_consistency fuzz target. These
variants were reachable but not matched, causing panics on the wildcard
arm ("Unhandled message event").

SendTxInitRbf became reachable after commit 5873660 added splicing
support without updating the fuzz target's message delivery logic.

AI tools were used in preparing this commit.

Author: joostjager

fuzz/src/chanmon_consistency.rs

@@ -1529,6 +1529,14 @@ pub fn do_test<Out: Output + MaybeSend + MaybeSync>(
 							if Some(*node_id) == expect_drop_id { panic!("peer_disconnected should drop msgs bound for the disconnected peer"); }
 							*node_id == a_id
 						},
+						MessageSendEvent::SendTxRemoveInput { ref node_id, .. } => {
+							if Some(*node_id) == expect_drop_id { panic!("peer_disconnected should drop msgs bound for the disconnected peer"); }
+							*node_id == a_id
+						},
+						MessageSendEvent::SendTxRemoveOutput { ref node_id, .. } => {
+							if Some(*node_id) == expect_drop_id { panic!("peer_disconnected should drop msgs bound for the disconnected peer"); }
+							*node_id == a_id
+						},
 						MessageSendEvent::SendTxComplete { ref node_id, .. } => {
 							if Some(*node_id) == expect_drop_id { panic!("peer_disconnected should drop msgs bound for the disconnected peer"); }
 							*node_id == a_id
@@ -1537,6 +1545,14 @@ pub fn do_test<Out: Output + MaybeSend + MaybeSync>(
 							if Some(*node_id) == expect_drop_id { panic!("peer_disconnected should drop msgs bound for the disconnected peer"); }
 							*node_id == a_id
 						},
+						MessageSendEvent::SendTxInitRbf { ref node_id, .. } => {
+							if Some(*node_id) == expect_drop_id { panic!("peer_disconnected should drop msgs bound for the disconnected peer"); }
+							*node_id == a_id
+						},
+						MessageSendEvent::SendTxAckRbf { ref node_id, .. } => {
+							if Some(*node_id) == expect_drop_id { panic!("peer_disconnected should drop msgs bound for the disconnected peer"); }
+							*node_id == a_id
+						},
 						MessageSendEvent::SendTxSignatures { ref node_id, .. } => {
 							if Some(*node_id) == expect_drop_id { panic!("peer_disconnected should drop msgs bound for the disconnected peer"); }
 							*node_id == a_id
@@ -1729,6 +1745,22 @@ pub fn do_test<Out: Output + MaybeSend + MaybeSync>(
 								}
 							}
 						},
+						MessageSendEvent::SendTxInitRbf { ref node_id, ref msg } => {
+							for (idx, dest) in nodes.iter().enumerate() {
+								if dest.get_our_node_id() == *node_id {
+									out.locked_write(format!("Delivering tx_init_rbf from node {} to node {}.\n", $node, idx).as_bytes());
+									dest.handle_tx_init_rbf(nodes[$node].get_our_node_id(), msg);
+								}
+							}
+						},
+						MessageSendEvent::SendTxAckRbf { ref node_id, ref msg } => {
+							for (idx, dest) in nodes.iter().enumerate() {
+								if dest.get_our_node_id() == *node_id {
+									out.locked_write(format!("Delivering tx_ack_rbf from node {} to node {}.\n", $node, idx).as_bytes());
+									dest.handle_tx_ack_rbf(nodes[$node].get_our_node_id(), msg);
+								}
+							}
+						},
 						MessageSendEvent::SendTxSignatures { ref node_id, ref msg } => {
 							for (idx, dest) in nodes.iter().enumerate() {
 								if dest.get_our_node_id() == *node_id {