Stop the sync loop after each background app refresh. (#3481)

ElementX/Sources/Application/AppCoordinator.swift

@@ -988,7 +988,8 @@ class AppCoordinator: AppCoordinatorProtocol, AuthenticationFlowCoordinatorDeleg
         // This is important for the app to keep refreshing in the background
         scheduleBackgroundAppRefresh()
         
-        task.expirationHandler = {
+        task.expirationHandler = { [weak self] in
+            self?.stopSync() // Attempt to stop the sync loop cleanly.
             MXLog.info("Background app refresh task expired")
             task.setTaskCompleted(success: true)
         }
@@ -1007,8 +1008,11 @@ class AppCoordinator: AppCoordinatorProtocol, AuthenticationFlowCoordinatorDeleg
             .collect(.byTimeOrCount(DispatchQueue.main, .seconds(10), 10))
             .sink(receiveValue: { [weak self] _ in
                 guard let self else { return }
-                
                 MXLog.info("Background app refresh finished")
+                
+                // Make sure we stop the sync loop, otherwise the ongoing request is immediately
+                // handled the next time the app refreshes, which can trigger timeout failures.
+                stopSync()
                 backgroundRefreshSyncObserver?.cancel()
                 
                 task.setTaskCompleted(success: true)

ElementX/Sources/Services/Client/ClientProxy.swift

@@ -306,15 +306,24 @@ class ClientProxy: ClientProxyProtocol {
             restartTask = nil
         }
         
+        guard let syncService else {
+            MXLog.warning("No sync service to stop.")
+            completion?()
+            return
+        }
+        
         // Capture the sync service strongly as this method is called on deinit and so the
         // existence of self when the Task executes is questionable and would sometimes crash.
+        // Note: This isn't strictly necessary now given the unwrap above, but leaving the code as
+        // documentation. SE-0371 will allow us to fix this by using an async deinit.
         Task { [syncService] in
             do {
                 defer {
                     completion?()
                 }
                 
-                try await syncService?.stop()
+                try await syncService.stop()
+                MXLog.info("Sync stopped")
             } catch {
                 MXLog.error("Failed stopping the sync service with error: \(error)")
             }