Handle configuration errors out of VPN status

On configuration error, retain information about the profile that
triggered the error. For now, present an alert, but with this
information the UI can be easily changed later.

Passepartout/App/L10n/Core+L10n.swift

@@ -26,6 +26,15 @@
 import Foundation
 import PassepartoutCore
 
+extension Error {
+    var localizedAppDescription: String {
+        if let errorDescription = (self as? PassepartoutError)?.localizedAppDescription, !errorDescription.isEmpty {
+            return "\(errorDescription)."
+        }
+        return localizedDescription
+    }
+}
+
 extension PassepartoutError {
     var localizedAppDescription: String? {
         let V = L10n.Global.Errors.self

Passepartout/App/Views/OrganizerView.swift

@@ -30,7 +30,7 @@ struct OrganizerView: View {
     enum AlertType: Identifiable {
         case subscribeReddit
         
-        case error(String, Error)
+        case error(String, String)
         
         // XXX: alert ids
         var id: Int {
@@ -79,6 +79,11 @@ struct OrganizerView: View {
             onCompletion: onHostFileImporterResult
         ).onOpenURL(perform: onOpenURL)
         .themePrimaryView()
+        
+        // VPN configuration error publisher (no need to observe VPNManager)
+        .onReceive(VPNManager.shared.configurationError) {
+            alertType = .error($0.profile.header.name, $0.error.localizedAppDescription)
+        }
     }
     
     private var hiddenSceneView: some View {
@@ -105,7 +110,7 @@ extension OrganizerView {
         case .failure(let error):
             alertType = .error(
                 L10n.Menu.Contextual.AddProfile.fromFiles,
-                error
+                error.localizedDescription
             )
         }
     }
@@ -129,10 +134,10 @@ extension OrganizerView {
                 }
             )
 
-        case .error(let title, let error):
+        case .error(let title, let errorDescription):
             return Alert(
                 title: Text(title),
-                message: Text(error.localizedDescription),
+                message: Text(errorDescription),
                 dismissButton: .cancel(Text(L10n.Global.Strings.ok))
             )
         }

PassepartoutCore/Sources/PassepartoutCore/Managers/VPNManager+Configuration.swift

@@ -87,7 +87,7 @@ extension VPNManager {
             pp_log.error("Unable to build VPNConfiguration: \(error)")
 
             // UI is certainly interested in configuration errors
-            lastError = error
+            configurationError.send((profile, error))
 
             throw error
         }

PassepartoutCore/Sources/PassepartoutCore/Managers/VPNManager.swift

@@ -30,6 +30,7 @@ import TunnelKitOpenVPNManager
 
 @MainActor
 public class VPNManager: ObservableObject {
+    public typealias ConfigurationError = (profile: Profile, error: Error)
 
     // MARK: Initialization
     
@@ -49,7 +50,7 @@ public class VPNManager: ObservableObject {
     
     public let currentState: ObservableState
     
-    public internal(set) var lastError: Error? {
+    public private(set) var lastError: Error? {
         get {
             currentState.lastError
         }
@@ -58,6 +59,8 @@ public class VPNManager: ObservableObject {
         }
     }
     
+    public let configurationError = PassthroughSubject<ConfigurationError, Never>()
+    
     // MARK: Internals
     
     private var lastProfile: Profile = .placeholder