Refactor DNUpdater to an actor and try to fix warnings

ios/NebulaNetworkExtension/PacketTunnelProvider.swift

@@ -23,7 +23,7 @@ extension AppMessageError: LocalizedError {
     }
 }
 
-class PacketTunnelProvider: NEPacketTunnelProvider {
+final class PacketTunnelProvider: NEPacketTunnelProvider, @unchecked Sendable {
     private var networkMonitor: NWPathMonitor?
 
     private var site: Site?
@@ -115,7 +115,7 @@ class PacketTunnelProvider: NEPacketTunnelProvider {
         }
 
         nebula!.start()
-        dnUpdater.updateSingleLoop(site: site!, onUpdate: handleDNUpdate)
+        await dnUpdater.updateSingleLoop(site: site!, onUpdate: handleDNUpdate)
     }
 
     private func handleDNUpdate(newSite: Site) {

ios/NebulaNetworkExtension/Site.swift

@@ -150,7 +150,7 @@ let statusString: [NEVPNStatus: String] = [
 ]
 
 // Represents a site that was pulled out of the system configuration
-class Site: Codable {
+final class Site: Codable, @unchecked Sendable {
     // Stored in manager
     var name: String
     var id: String
@@ -278,7 +278,7 @@ class Site: Codable {
                 }
             }
 
-            if hasErrors && !managed {
+            if hasErrors, !managed {
                 errors.append("There are issues with 1 or more ca certificates")
             }
 
@@ -294,7 +294,7 @@ class Site: Codable {
             errors.append("Unable to create the site directory: \(error.localizedDescription)")
         }
 
-        if managed && (try? getDNCredentials())?.invalid != false {
+        if managed, (try? getDNCredentials())?.invalid != false {
             errors.append("Unable to fetch managed updates - please re-enroll the device")
         }
 
@@ -426,7 +426,7 @@ class DNCredentials: Codable {
 }
 
 // This class represents a site coming in from flutter, meant only to be saved and re-loaded as a proper Site
-struct IncomingSite: Codable {
+struct IncomingSite: Codable, @unchecked Sendable {
     var name: String
     var id: String
     var staticHostmap: [String: StaticHosts]

ios/Runner/AppDelegate.swift

@@ -25,7 +25,8 @@ func MissingArgumentError(message: String, details: Any?) -> FlutterError {
     ) -> Bool {
         GeneratedPluginRegistrant.register(with: self)
 
-        dnUpdater.updateAllLoop { site in
+        Task {
+            await dnUpdater.updateAllLoop { @MainActor site in
                 // Signal the site has changed in case the current site details screen is active
                 let container = self.sites?.getContainer(id: site.id)
                 if container != nil {
@@ -37,6 +38,7 @@ func MissingArgumentError(message: String, details: Any?) -> FlutterError {
                 // Signal to the main screen to reload
                 self.ui?.invokeMethod("refreshSites", arguments: nil)
             }
+        }
 
         guard let controller = window?.rootViewController as? FlutterViewController else {
             fatalError("rootViewController is not type FlutterViewController")

ios/Runner/DNUpdate.swift

@@ -1,29 +1,33 @@
 import Foundation
 import os.log
 
-class DNUpdater {
+actor DNUpdater {
     private let apiClient = APIClient()
     private let timer = RepeatingTimer(timeInterval: 15 * 60) // 15 * 60 is 15 minutes
     private let log = Logger(subsystem: "net.defined.mobileNebula", category: "DNUpdater")
 
-    func updateAll(onUpdate: @escaping (Site) -> Void) {
+    func updateAll(onUpdate: @Sendable @escaping (Site) -> Void) {
         _ = SiteList { sites, _ in
+            guard let unwrappedSites = sites else {
+                // There was an error, let's bail.
+                return
+            }
             // NEVPN seems to force us onto the main thread and we are about to make network calls that
             // could block for a while. Push ourselves onto another thread to avoid blocking the UI.
             Task.detached(priority: .userInitiated) {
-                sites?.values.forEach { site in
+                for site in unwrappedSites.values {
                     if site.connected == true {
                         // The vpn service is in charge of updating the currently connected site
                         return
                     }
 
-                    self.updateSite(site: site, onUpdate: onUpdate)
+                    await self.updateSite(site: site, onUpdate: onUpdate)
                 }
             }
         }
     }
 
-    func updateAllLoop(onUpdate: @escaping (Site) -> Void) {
+    func updateAllLoop(onUpdate: @Sendable @escaping (Site) -> Void) {
         timer.eventHandler = {
             self.updateAll(onUpdate: onUpdate)
         }
@@ -37,7 +41,7 @@ class DNUpdater {
         timer.resume()
     }
 
-    func updateSite(site: Site, onUpdate: @escaping (Site) -> Void) {
+    func updateSite(site: Site, onUpdate: sending @escaping (Site) -> Void) {
         do {
             if !site.managed {
                 return