edit

XLAB2/App.xaml.cs

@@ -4,6 +4,7 @@ using System.Threading;
 using System.Threading.Tasks;
 using System.Windows;
 using System.Windows.Markup;
+using System.Windows.Threading;
 using Microsoft.Extensions.DependencyInjection;
 using Microsoft.Extensions.Hosting;
 using XLAB2.Infrastructure;
@@ -17,6 +18,7 @@ namespace XLAB2
         public App()
         {
             ApplyRussianCulture();
+            RegisterGlobalExceptionHandlers();
         }
 
         protected override async void OnStartup(StartupEventArgs e)
@@ -40,19 +42,29 @@ namespace XLAB2
 
         protected override async void OnExit(ExitEventArgs e)
         {
-            if (_host != null)
+            try
             {
-                try
+                if (_host != null)
                 {
-                    await _host.StopAsync(TimeSpan.FromSeconds(5)).ConfigureAwait(true);
-                }
-                finally
-                {
-                    _host.Dispose();
+                    try
+                    {
+                        await _host.StopAsync(TimeSpan.FromSeconds(5)).ConfigureAwait(true);
+                    }
+                    finally
+                    {
+                        _host.Dispose();
+                    }
                 }
             }
-
-            base.OnExit(e);
+            catch (Exception ex)
+            {
+                ShowUnhandledException(ex, true);
+            }
+            finally
+            {
+                UnregisterGlobalExceptionHandlers();
+                base.OnExit(e);
+            }
         }
 
         private static void ApplyRussianCulture()
@@ -68,5 +80,77 @@ namespace XLAB2
                 typeof(FrameworkElement),
                 new FrameworkPropertyMetadata(XmlLanguage.GetLanguage(culture.IetfLanguageTag)));
         }
+
+        private void RegisterGlobalExceptionHandlers()
+        {
+            DispatcherUnhandledException += OnDispatcherUnhandledException;
+            AppDomain.CurrentDomain.UnhandledException += OnCurrentDomainUnhandledException;
+            TaskScheduler.UnobservedTaskException += OnUnobservedTaskException;
+        }
+
+        private void UnregisterGlobalExceptionHandlers()
+        {
+            DispatcherUnhandledException -= OnDispatcherUnhandledException;
+            AppDomain.CurrentDomain.UnhandledException -= OnCurrentDomainUnhandledException;
+            TaskScheduler.UnobservedTaskException -= OnUnobservedTaskException;
+        }
+
+        private void OnDispatcherUnhandledException(object sender, DispatcherUnhandledExceptionEventArgs e)
+        {
+            ShowUnhandledException(e.Exception, false);
+            e.Handled = true;
+        }
+
+        private void OnCurrentDomainUnhandledException(object sender, UnhandledExceptionEventArgs e)
+        {
+            var exception = e.ExceptionObject as Exception;
+            if (exception != null)
+            {
+                ShowUnhandledException(exception, e.IsTerminating);
+                return;
+            }
+
+            MessageBox.Show(
+                e.ExceptionObject == null ? "Произошла необработанная ошибка." : e.ExceptionObject.ToString(),
+                e.IsTerminating ? "XLAB2 - критическая ошибка" : "XLAB2",
+                MessageBoxButton.OK,
+                MessageBoxImage.Error);
+        }
+
+        private void OnUnobservedTaskException(object sender, UnobservedTaskExceptionEventArgs e)
+        {
+            ShowUnhandledException(e.Exception, false);
+            e.SetObserved();
+        }
+
+        private static void ShowUnhandledException(Exception exception, bool isCritical)
+        {
+            var actualException = UnwrapException(exception);
+            var message = string.IsNullOrWhiteSpace(actualException.Message)
+                ? actualException.ToString()
+                : actualException.Message;
+
+            MessageBox.Show(
+                message,
+                isCritical ? "XLAB2 - критическая ошибка" : "XLAB2",
+                MessageBoxButton.OK,
+                MessageBoxImage.Error);
+        }
+
+        private static Exception UnwrapException(Exception exception)
+        {
+            if (exception is AggregateException aggregateException)
+            {
+                var flattened = aggregateException.Flatten();
+                if (flattened.InnerExceptions.Count == 1)
+                {
+                    return UnwrapException(flattened.InnerExceptions[0]);
+                }
+
+                return flattened;
+            }
+
+            return exception;
+        }
     }
 }