DYN-6492 add unhandled exception handler to viewmodel (#14840)

* add unhandled exception handler to viewmodel

* cleanup

* add backup crash dialog if CER is unavailable

* catch any exceptions thrown from handler itself

Author: aparajit-pratap

src/DynamoCoreWpf/ViewModels/Core/DynamoViewModel.cs

@@ -14,6 +14,7 @@
 using System.Windows.Media;
 using System.Windows.Threading;
 using Dynamo.Configuration;
+using Dynamo.Core;
 using Dynamo.Engine;
 using Dynamo.Exceptions;
 using Dynamo.Graph;
@@ -22,6 +23,7 @@
 using Dynamo.Graph.Nodes;
 using Dynamo.Graph.Workspaces;
 using Dynamo.Interfaces;
+using Dynamo.Logging;
 using Dynamo.Models;
 using Dynamo.PackageManager;
 using Dynamo.PackageManager.UI;
@@ -30,7 +32,6 @@
 using Dynamo.Services;
 using Dynamo.UI;
 using Dynamo.UI.Prompts;
-using Dynamo.Updates;
 using Dynamo.Utilities;
 using Dynamo.Visualization;
 using Dynamo.Wpf.Interfaces;
@@ -675,6 +676,8 @@ public struct StartConfiguration
 
         protected DynamoViewModel(StartConfiguration startConfiguration)
         {
+            Dispatcher.CurrentDispatcher.UnhandledException += CurrentDispatcher_UnhandledException;
+
             this.ShowLogin = startConfiguration.ShowLogin;
 
             // initialize core data structures
@@ -754,6 +757,33 @@ protected DynamoViewModel(StartConfiguration startConfiguration)
             FileTrustViewModel = new FileTrustWarningViewModel();
         }
 
+        private void CurrentDispatcher_UnhandledException(object sender, DispatcherUnhandledExceptionEventArgs e)
+        {
+            if (e.Handled)
+            {
+                return;
+            }
+
+            e.Handled = true;
+            CrashGracefully(e.Exception);
+        }
+
+        private void CrashGracefully(Exception ex)
+        {
+            try
+            {
+                Model?.Logger?.LogError($"Unhandled exception {ex.Message}");
+
+                DynamoModel.IsCrashing = true;
+                Analytics.TrackException(ex, true);
+                Model?.OnRequestsCrashPrompt(new CrashErrorReportArgs(ex));
+
+                Exit(false); // don't allow cancellation
+            }
+            catch
+            { }
+        }
+
         /// <summary>
         /// Sets up the provided <see cref="DefaultWatch3DViewModel"/> object and 
         /// adds it to the Watch3DViewModels collection.
@@ -3412,6 +3442,8 @@ public ShutdownParams(
         /// 
         public bool PerformShutdownSequence(ShutdownParams shutdownParams)
         {
+            Dispatcher.CurrentDispatcher.UnhandledException -= CurrentDispatcher_UnhandledException;
+
             if (shutdownSequenceInitiated)
             {
                 // There was a prior call to shutdown. This could happen for example