Fill missing descriptions for some errors (#359)

Fixes #358

Passepartout/App/L10n/OpenVPN+L10n.swift

@@ -259,7 +259,7 @@ extension TunnelKitOpenVPNError: LocalizedError {
         case .serverCompression, .lzo:
             return V.compression
 
-        case .networkChanged:
+        case .networkChanged, .linkError:
             return V.network
 
         case .routing:
@@ -272,7 +272,7 @@ extension TunnelKitOpenVPNError: LocalizedError {
             return V.shutdown
 
         default:
-            return nil
+            return L10n.Global.unknown
         }
     }
 }
@@ -306,7 +306,7 @@ extension OpenVPN.ConfigurationError: LocalizedError {
 
         case .continuationPushReply:
             assertionFailure("This is a server-side configuration parsing error")
-            return nil
+            return L10n.Global.Strings.unknown
         }
     }
 }

Passepartout/App/L10n/WireGuard+L10n.swift

@@ -62,7 +62,7 @@ extension TunnelKitWireGuardError: LocalizedError {
             return V.dns
 
         default:
-            return nil
+            return L10n.Global.unknown
         }
     }
 }

Passepartout/App/en.lproj/Localizable.strings

@@ -54,6 +54,7 @@
 "global.strings.policy" = "Policy";
 "global.strings.networks" = "Networks";
 "global.strings.edit" = "Edit";
+"global.strings.unknown" = "Unknown";
 "global.messages.unlock_app" = "Passepartout is locked";
 "global.messages.email_not_configured" = "No e-mail account is configured.";
 "global.messages.share" = "Passepartout is a user-friendly, open source OpenVPN / WireGuard client for iOS and macOS";

Passepartout/AppShared/Constants/SwiftGen+Strings.swift

@@ -550,6 +550,8 @@ internal enum L10n {
       internal static let translations = L10n.tr("Localizable", "global.strings.translations", fallback: "Translations")
       /// Uninstall
       internal static let uninstall = L10n.tr("Localizable", "global.strings.uninstall", fallback: "Uninstall")
+      /// Unknown
+      internal static let unknown = L10n.tr("Localizable", "global.strings.unknown", fallback: "Unknown")
     }
   }
   internal enum Menu {