Start using the new synchronous stopSync method

ElementX/Sources/Application/AppCoordinator.swift

@@ -554,14 +554,13 @@ class AppCoordinator: AppCoordinatorProtocol, AuthenticationCoordinatorDelegate,
         backgroundTask = backgroundTaskService.startBackgroundTask(withName: "SuspendApp: \(UUID().uuidString)") { [weak self] in
             guard let self else { return }
             
-            userSession?.clientProxy.stopSync {
-                // No need to weakify self, this is a non escaping closure
-                self.backgroundTask?.stop()
-                self.backgroundTask = nil
-                
-                self.backgroundAppRefreshTask?.setTaskCompleted(success: true)
-                self.backgroundAppRefreshTask = nil
-            }
+            userSession?.clientProxy.stopSync()
+            
+            backgroundTask?.stop()
+            backgroundTask = nil
+            
+            backgroundAppRefreshTask?.setTaskCompleted(success: true)
+            backgroundAppRefreshTask = nil
         }
 
         isSuspended = true

ElementX/Sources/Services/Client/ClientProxy.swift

@@ -166,19 +166,9 @@ class ClientProxy: ClientProxyProtocol {
         slidingSyncObserverToken = slidingSync?.sync()
     }
 
-    func stopSync(completionHandler: () -> Void) {
-        guard let slidingSyncObserverToken else {
-            MXLog.info("No sync is present")
-            return
-        }
-        stopSync()
-        while !slidingSyncObserverToken.isFinished() { }
-        completionHandler()
-    }
-
     func stopSync() {
         MXLog.info("Stopping sync")
-        slidingSyncObserverToken?.cancel()
+        slidingSync?.stopSync()
         slidingSyncObserverToken = nil
     }
     

ElementX/Sources/Services/Client/ClientProxyProtocol.swift

@@ -86,10 +86,6 @@ protocol ClientProxyProtocol: AnyObject, MediaLoaderProtocol {
     
     func startSync()
 
-    /// Stops the sync usiung non escaping closure.
-    /// It's supposed to be used for the expiration handlers to guarantee its synchronous execution
-    func stopSync(completionHandler: () -> Void)
-
     func stopSync()
     
     func directRoomForUserID(_ userID: String) async -> Result<String?, ClientProxyError>