Functionize the UNFUNDED case in convert_channel_err

`convert_channel_err` is used extensively in `channelmanager.rs`
(often indirectly via `try_channel_entry`) and generates nontrivial
code (especially once you include `locked_close_channel`). Here we
take the `UNFUNDED` case of it and move them to an internal
function reducing the generated code size.

On the same machine as described three commits ago, this further
reduces build times from the previous commit by about another
second.

Author: TheBlueMatt

lightning/src/ln/channelmanager.rs

@@ -3710,6 +3710,27 @@ where
 	})
 }
 
+fn convert_unfunded_channel_err_internal<
+	SP: Deref,
+	CM: AChannelManager,
+>(
+	cm: &CM, err: ChannelError, chan: &mut Channel<SP>,
+) -> (bool, MsgHandleErrInternal)
+where
+	SP::Target: SignerProvider,
+{
+	let chan_id = chan.context().channel_id();
+	convert_channel_err_internal(err, chan_id, |reason, msg| {
+		let cm = cm.get_cm();
+		let logger = WithChannelContext::from(&cm.logger, chan.context(), None);
+
+		let shutdown_res = chan.force_shutdown(reason);
+		log_error!(logger, "Closed channel {} due to close-required error: {}", chan_id, msg);
+		locked_close_channel!(cm, chan.context(), UNFUNDED);
+		(shutdown_res, None)
+	})
+}
+
 /// When a channel is removed, two things need to happen:
 /// (a) This must be called in the same `per_peer_state` lock as the channel-closing action,
 /// (b) [`handle_error`] needs to be called without holding any locks (except
@@ -3724,34 +3745,6 @@ where
 /// true).
 #[rustfmt::skip]
 macro_rules! convert_channel_err {
-	($self: ident, $peer_state: expr, $err: expr, $chan: expr, $close: expr, $locked_close: expr, $channel_id: expr, _internal) => { {
-		match $err {
-			ChannelError::Warn(msg) => {
-				(false, MsgHandleErrInternal::from_chan_no_close(ChannelError::Warn(msg), $channel_id))
-			},
-			ChannelError::WarnAndDisconnect(msg) => {
-				(false, MsgHandleErrInternal::from_chan_no_close(ChannelError::WarnAndDisconnect(msg), $channel_id))
-			},
-			ChannelError::Ignore(msg) => {
-				(false, MsgHandleErrInternal::from_chan_no_close(ChannelError::Ignore(msg), $channel_id))
-			},
-			ChannelError::Abort(reason) => {
-				(false, MsgHandleErrInternal::from_chan_no_close(ChannelError::Abort(reason), $channel_id))
-			},
-			ChannelError::Close((msg, reason)) => {
-				let (mut shutdown_res, chan_update) = $close(reason);
-				let logger = WithChannelContext::from(&$self.logger, &$chan.context(), None);
-				log_error!(logger, "Closed channel {} due to close-required error: {}", $channel_id, msg);
-				$locked_close(&mut shutdown_res, $chan);
-				let err =
-					MsgHandleErrInternal::from_finish_shutdown(msg, $channel_id, shutdown_res, chan_update);
-				(true, err)
-			},
-			ChannelError::SendError(msg) => {
-				(false, MsgHandleErrInternal::from_chan_no_close(ChannelError::SendError(msg), $channel_id))
-			},
-		}
-	} };
 	($self: ident, $peer_state: expr, $shutdown_result: expr, $funded_channel: expr, COOP_CLOSED) => { {
 		let reason = ChannelError::Close(("Coop Closed".to_owned(), $shutdown_result.closure_reason.clone()));
 		let closed_update_ids = &mut $peer_state.closed_channel_monitor_update_ids;
@@ -3768,10 +3761,7 @@ macro_rules! convert_channel_err {
 		convert_funded_channel_err_internal($self, closed_update_ids, in_flight_updates, None, $err, $funded_channel)
 	} };
 	($self: ident, $peer_state: expr, $err: expr, $channel: expr, UNFUNDED_CHANNEL) => { {
-		let chan_id = $channel.context().channel_id();
-		let mut do_close = |reason| { ($channel.force_shutdown(reason), None) };
-		let locked_close = |_, chan: &mut Channel<_>| { locked_close_channel!($self, chan.context(), UNFUNDED); };
-		convert_channel_err!($self, $peer_state, $err, $channel, do_close, locked_close, chan_id, _internal)
+		convert_unfunded_channel_err_internal($self, $err, $channel)
 	} };
 	($self: ident, $peer_state: expr, $err: expr, $channel: expr) => {
 		match $channel.as_funded_mut() {
@@ -3781,7 +3771,7 @@ macro_rules! convert_channel_err {
 				convert_funded_channel_err_internal($self, closed_update_ids, in_flight_updates, None, $err, funded_channel)
 			},
 			None => {
-				convert_channel_err!($self, $peer_state, $err, $channel, UNFUNDED_CHANNEL)
+				convert_unfunded_channel_err_internal($self, $err, $channel)
 			},
 		}
 	};