server: start htlcSwitch before chainArb

docs/release-notes/release-notes-0.15.0.md

@@ -36,6 +36,10 @@
   could result in an "invoice too large" error when creating invoices. Hints 
   are now properly limited to our maximum of 20.
 
+* [Fixed an edge case where the lnd might be stuck at starting due to channel
+  arbitrator relying on htlcswitch to be started
+  first](https://github.com/lightningnetwork/lnd/pull/6214).
+
 ## Misc
 
 * [An example systemd service file](https://github.com/lightningnetwork/lnd/pull/6033)

server.go

@@ -1777,6 +1777,15 @@ func (s *server) Start() error {
 		}
 		cleanup = cleanup.add(s.fundingMgr.Stop)
 
+		// htlcSwitch must be started before chainArb since the latter
+		// relies on htlcSwitch to deliver resolution message upon
+		// start.
+		if err := s.htlcSwitch.Start(); err != nil {
+			startErr = err
+			return
+		}
+		cleanup = cleanup.add(s.htlcSwitch.Stop)
+
 		if err := s.chainArb.Start(); err != nil {
 			startErr = err
 			return
@@ -1807,12 +1816,6 @@ func (s *server) Start() error {
 		}
 		cleanup = cleanup.add(s.sphinx.Stop)
 
-		if err := s.htlcSwitch.Start(); err != nil {
-			startErr = err
-			return
-		}
-		cleanup = cleanup.add(s.htlcSwitch.Stop)
-
 		if err := s.chanStatusMgr.Start(); err != nil {
 			startErr = err
 			return