Customize error messages for connection failures.

lib/app/views/app_failure_screen.dart

@@ -1,18 +1,46 @@
+import 'dart:io';
+
 import 'package:flutter/material.dart';
+import 'package:yubico_authenticator/desktop/models.dart';
 
 class AppFailureScreen extends StatelessWidget {
-  final String reason;
+  final Object reason;
   const AppFailureScreen(this.reason, {super.key}) : super();
 
   @override
   Widget build(BuildContext context) {
+    final cause = reason;
+    if (cause is RpcError) {
+      if (cause.status == 'connection-error' &&
+          cause.body['connection'] == 'ccid') {
+        var msg = 'Failed to open smart card connection';
+        if (Platform.isMacOS) {
+          msg += '\nTry to remove and re-insert your YubiKey to regain access.';
+        } else if (Platform.isLinux) {
+          msg += '\nMake sure pcscd is running.';
+        }
+        return Center(
+          child: Column(
+            mainAxisAlignment: MainAxisAlignment.center,
+            crossAxisAlignment: CrossAxisAlignment.center,
+            children: [
+              Text(
+                msg,
+                textAlign: TextAlign.center,
+              ),
+            ],
+          ),
+        );
+      }
+    }
+
     return Center(
       child: Column(
         mainAxisAlignment: MainAxisAlignment.center,
         crossAxisAlignment: CrossAxisAlignment.center,
         children: [
           Text(
-            reason,
+            cause.toString(),
             textAlign: TextAlign.center,
           ),
         ],

lib/fido/views/fido_screen.dart

@@ -10,6 +10,7 @@ import '../../app/views/app_loading_screen.dart';
 import '../../app/views/app_page.dart';
 import '../../app/views/graphics.dart';
 import '../../app/views/message_page.dart';
+import '../../desktop/models.dart';
 import '../../desktop/state.dart';
 import '../../management/models.dart';
 import '../../theme.dart';
@@ -52,9 +53,10 @@ class FidoScreen extends ConsumerWidget {
                     'WebAuthn requires the FIDO2 application to be enabled on your YubiKey',
               );
             }
-            if (Platform.isWindows) {
-              if (!ref
-                  .watch(rpcStateProvider.select((state) => state.isAdmin))) {
+            if (Platform.isWindows && error is RpcError) {
+              if (error.status == 'connection-error' &&
+                  !ref.watch(
+                      rpcStateProvider.select((state) => state.isAdmin))) {
                 return MessagePage(
                   title: const Text('WebAuthn'),
                   graphic: noPermission,
@@ -85,7 +87,7 @@ class FidoScreen extends ConsumerWidget {
             return AppPage(
               title: const Text('WebAuthn'),
               centered: true,
-              child: AppFailureScreen('$error'),
+              child: AppFailureScreen(error),
             );
           },
           data: (fidoState) {

lib/management/views/management_screen.dart

@@ -241,7 +241,7 @@ class _ManagementScreenState extends ConsumerState<ManagementScreen> {
     final child =
         ref.watch(managementStateProvider(widget.deviceData.node.path)).when(
               loading: () => const AppLoadingScreen(),
-              error: (error, _) => AppFailureScreen('$error'),
+              error: (error, _) => AppFailureScreen(error),
               data: (info) {
                 bool hasConfig = info.version.major > 4;
                 if (hasConfig) {

lib/oath/views/oath_screen.dart

@@ -34,7 +34,7 @@ class OathScreen extends ConsumerWidget {
           error: (error, _) => AppPage(
             title: const Text('Authenticator'),
             centered: true,
-            child: AppFailureScreen('$error'),
+            child: AppFailureScreen(error),
           ),
           data: (oathState) => oathState.locked
               ? _LockedView(devicePath, oathState)