Don't close a funded channel on splice failure

If splicing fails, the previous funding is still usable. Convert any
ChannelError::Close to ChannelClose::Warn when this is the case to avoid
closing a usable channel.

Author: jkczyz

lightning/src/ln/channel.rs

@@ -1809,13 +1809,23 @@ where
 						{
 							let mut signing_session =
 								interactive_tx_constructor.into_signing_session();
-							let (commitment_signed, event) = chan.context.funding_tx_constructed(
-								&mut funding,
-								&mut signing_session,
-								true,
-								chan.holder_commitment_point.transaction_number(),
-								&&logger,
-							)?;
+							let (commitment_signed, event) = chan
+								.context
+								.funding_tx_constructed(
+									&mut funding,
+									&mut signing_session,
+									true,
+									chan.holder_commitment_point.transaction_number(),
+									&&logger,
+								)
+								// Don't close a funded channel if splicing fails
+								.map_err(|e| {
+									if let ChannelError::Close((message, _)) = e {
+										ChannelError::Warn(message)
+									} else {
+										e
+									}
+								})?;
 
 							chan.interactive_tx_signing_session = Some(signing_session);
 							pending_splice.funding_negotiation =

lightning/src/ln/channelmanager.rs

@@ -9730,10 +9730,12 @@ This indicates a bug inside LDK. Please report this error at https://github.com/
 					peer_state.pending_msg_events.push(msg_send_event);
 				};
 				if negotiation_complete {
-					let (commitment_signed, funding_ready_for_sig_event_opt) = chan_entry
-						.get_mut()
-						.funding_tx_constructed(&self.logger)
-						.map_err(|err| MsgHandleErrInternal::send_err_msg_no_close(format!("{}", err), msg.channel_id))?;
+					let (commitment_signed, funding_ready_for_sig_event_opt) = try_channel_entry!(
+						self,
+						peer_state,
+						chan_entry.get_mut().funding_tx_constructed(&self.logger),
+						chan_entry
+					);
 					if let Some(funding_ready_for_sig_event) = funding_ready_for_sig_event_opt {
 						let mut pending_events = self.pending_events.lock().unwrap();
 						pending_events.push_back((funding_ready_for_sig_event, None));