Merged PR 10778666: Recall | Show error dialog if launching from snapshot has failed

## What
Per Figma design, we can show an error dialog with messages for the failures happens during snapshot launch.

## Notes
- Fixed a crash about taking a snapshot when Calculator hasn't initialized a standard calculator.
- Simplified the restore path.

## Screenshot
![image.png](https://dev.azure.com/microsoft/d1a24475-535d-4c83-988a-9491e6dbc858/_apis/git/repositories/6255259e-4ead-4d8d-b165-55eeacc5ca48/pullRequests/10778666/attachments/image.png)

Related work items: #50858262

src/CalcViewModel/ApplicationViewModel.cpp

@@ -710,8 +710,9 @@ Windows::Data::Json::JsonObject ^ ApplicationViewModel::SaveApplicationSnapshot(
     ApplicationSnapshot applicationSnapshot;
     applicationSnapshot.SnapshotVersion = SnapshotHelper::SnapshotVersion;
     applicationSnapshot.Mode = static_cast<int>(Mode);
-    if (NavCategory::IsCalculatorViewMode(m_mode) && m_CalculatorViewModel != nullptr)
+    if (m_CalculatorViewModel != nullptr && m_mode == ViewMode::Standard)
     {
+        // Standard calculator is the only supported mode so far.
         applicationSnapshot.StandardCalc = m_CalculatorViewModel->GetStandardCalculatorSnapshot();
     }
     return SnapshotHelper::SaveSnapshotToJson(applicationSnapshot);

src/CalcViewModel/StandardCalculatorViewModel.cpp

@@ -1786,7 +1786,7 @@ void StandardCalculatorViewModel::SetBitshiftRadioButtonCheckedAnnouncement(Plat
 StandardCalculatorSnapshot StandardCalculatorViewModel::GetStandardCalculatorSnapshot() const
 {
     StandardCalculatorSnapshot snapshot;
-    auto historyItems = m_standardCalculatorManager.GetHistoryItems();
+    auto& historyItems = m_standardCalculatorManager.GetHistoryItems();
     if (!historyItems.empty())
     {
         snapshot.CalcManager.HistoryItems = std::move(historyItems);

src/Calculator/Resources/en-US/Resources.resw

@@ -4754,4 +4754,12 @@
     <value>Open the context menu for available actions</value>
     <comment>Screen reader prompt for the context menu of the expression box</comment>
   </data>
+  <data name="ErrorButtonOk" xml:space="preserve">
+    <value>OK</value>
+    <comment>The text of OK button to dismiss an error dialog.</comment>
+  </data>
+  <data name="SnapshotRestoreError" xml:space="preserve">
+    <value>Couldn't restore this snapshot.</value>
+    <comment>The error message to notify user that restoring from snapshot has failed.</comment>
+  </data>
 </root>

src/Calculator/Views/MainPage.xaml.cs

@@ -1,6 +1,7 @@
 using System;
 using System.Collections.Generic;
 using System.ComponentModel;
+using System.Threading.Tasks;
 
 using Windows.ApplicationModel.UserActivities;
 using Windows.Data.Json;
@@ -21,9 +22,11 @@ using CalculatorApp.ViewModel;
 using CalculatorApp.ViewModel.Common;
 using CalculatorApp.ViewModel.Common.Automation;
 
+using wuxc = Windows.UI.Xaml.Controls;
+
 namespace CalculatorApp
 {
-    public sealed partial class MainPage : Windows.UI.Xaml.Controls.Page
+    public sealed partial class MainPage : wuxc.Page
     {
         public static readonly DependencyProperty NavViewCategoriesSourceProperty =
             DependencyProperty.Register(nameof(NavViewCategoriesSource), typeof(List<object>), typeof(MainPage), new PropertyMetadata(default));
@@ -165,42 +168,19 @@ namespace CalculatorApp
                 {
                     var channel = UserActivityChannel.GetDefault();
                     var activity = await channel.GetOrCreateUserActivityAsync(snapshotArgs.ActivityId);
-                    if (!snapshotArgs.VerifyIncomingActivity(activity))
+
-                    {
+                    // Work around for bug https://microsoft.visualstudio.com/DefaultCollection/OS/_workitems/edit/48931227
-                        // something's going wrong with the activity
+                    // where ContentInfo can't be directly accessed.
-                        // TODO: show error dialog
+                    if (snapshotArgs.VerifyIncomingActivity(activity) &&
-                        return;
+                        JsonObject.TryParse(activity.ToJson(), out var activityJson) &&
-                    }
+                        activityJson.ContainsKey("contentInfo") &&
-                    else
+                        Model.TryRestoreFromSnapshot(activityJson.GetNamedObject("contentInfo")))
-                    {
-                        if (JsonObject.TryParse(activity.ToJson(), out var activityJson))
-                        {
-                            try
-                            {
-                                // Work around for bug https://microsoft.visualstudio.com/DefaultCollection/OS/_workitems/edit/48931227 where ContentInfo can't be directly accessed.
-                                var contentJson = activityJson.GetNamedObject("contentInfo");
-                                if (Model.TryRestoreFromSnapshot(contentJson))
                     {
                         SelectNavigationItemByModel();
                     }
                     else
                     {
-                                    // TODO: show error dialog
+                        await ShowSnapshotLaunchErrorAsync();
-                                    return;
-                                }
-                            }
-                            catch (Exception ex)
-                            {
-                                // TODO: show error dialog
-                                return;
-                            }
-                        }
-                        else
-                        {
-                            // data corrupted
-                            // TODO: show error dialog
-                            return;
-                        }
                     }
                 });
                 Model.Initialize(initialMode);
@@ -681,6 +661,19 @@ namespace CalculatorApp
             CloseSettingsPopup();
         }
 
+        private async Task ShowSnapshotLaunchErrorAsync()
+        {
+            var resProvider = AppResourceProvider.GetInstance();
+            var dialog = new wuxc.ContentDialog
+            {
+                Title = resProvider.GetResourceString("AppName"),
+                Content = new wuxc.TextBlock { Text = resProvider.GetResourceString("SnapshotRestoreError") },
+                CloseButtonText = resProvider.GetResourceString("ErrorButtonOk"),
+                DefaultButton = wuxc.ContentDialogButton.Close
+            };
+            await dialog.ShowAsync();
+        }
+
         private Calculator m_calculator;
         private GraphingCalculator m_graphingCalculator;
         private UnitConverter m_converter;