f clean up variable definition

Author: TheBlueMatt

lightning/src/ln/channelmanager.rs

@@ -2905,8 +2905,6 @@ macro_rules! handle_error {
 /// [`ChannelMonitor`]/channel funding transaction) to begin with.
 macro_rules! update_maps_on_chan_removal {
 	($self: expr, $peer_state: expr, $channel_context: expr) => {{
-		let chan_id = $channel_context.channel_id();
-
 		// If there's a possibility that we need to generate further monitor updates for this
 		// channel, we need to store the last update_id of it. However, we don't want to insert
 		// into the map (which prevents the `PeerState` from being cleaned up) for channels that
@@ -2930,6 +2928,7 @@ macro_rules! update_maps_on_chan_removal {
 					BackgroundEvent::MonitorUpdatesComplete { .. } => {},
 				}
 			}
+			let chan_id = $channel_context.channel_id();
 			$peer_state.closed_channel_monitor_update_ids.insert(chan_id, update_id);
 		}
 		if let Some(outpoint) = $channel_context.get_funding_txo() {