[GUI] Show error in a dialog when pull or export fails, instead of crashing the whole app

DiscordChatExporter.Gui/ViewModels/Dialogs/MessageBoxViewModel.cs

@@ -0,0 +1,27 @@
+using DiscordChatExporter.Gui.ViewModels.Framework;
+
+namespace DiscordChatExporter.Gui.ViewModels.Dialogs
+{
+    public class MessageBoxViewModel : DialogScreen
+    {
+        public string? Title { get; set; }
+
+        public string? Message { get; set; }
+    }
+
+    public static class MessageBoxViewModelExtensions
+    {
+        public static MessageBoxViewModel CreateMessageBoxViewModel(
+            this IViewModelFactory factory,
+            string title,
+            string message)
+        {
+            var viewModel = factory.CreateMessageBoxViewModel();
+
+            viewModel.Title = title;
+            viewModel.Message = message;
+
+            return viewModel;
+        }
+    }
+}

DiscordChatExporter.Gui/ViewModels/Framework/IViewModelFactory.cs

@@ -7,6 +7,8 @@ namespace DiscordChatExporter.Gui.ViewModels.Framework
     {
         ExportSetupViewModel CreateExportSetupViewModel();
 
+        MessageBoxViewModel CreateMessageBoxViewModel();
+
         SettingsViewModel CreateSettingsViewModel();
     }
 }

DiscordChatExporter.Gui/ViewModels/RootViewModel.cs

@@ -178,12 +178,23 @@ namespace DiscordChatExporter.Gui.ViewModels
             {
                 Notifications.Enqueue(ex.Message.TrimEnd('.'));
             }
+            catch (Exception ex)
+            {
+                var dialog = _viewModelFactory.CreateMessageBoxViewModel(
+                    "Error pulling guilds and channels",
+                    ex.ToString()
+                );
+
+                await _dialogManager.ShowDialogAsync(dialog);
+            }
         }
 
         public bool CanExportChannels =>
             !IsBusy && SelectedGuild is not null && SelectedChannels is not null && SelectedChannels.Any();
 
         public async void ExportChannels()
+        {
+            try
             {
                 var token = _settingsService.LastToken;
                 if (token is null || SelectedGuild is null || SelectedChannels is null || !SelectedChannels.Any())
@@ -236,5 +247,15 @@ namespace DiscordChatExporter.Gui.ViewModels
                 if (successfulExportCount > 0)
                     Notifications.Enqueue($"Successfully exported {successfulExportCount} channel(s)");
             }
+            catch (Exception ex)
+            {
+                var dialog = _viewModelFactory.CreateMessageBoxViewModel(
+                    "Error exporting channel(s)",
+                    ex.ToString()
+                );
+
+                await _dialogManager.ShowDialogAsync(dialog);
+            }
+        }
     }
 }

DiscordChatExporter.Gui/Views/Dialogs/MessageBoxView.xaml

@@ -0,0 +1,49 @@
+<UserControl
+    x:Class="DiscordChatExporter.Gui.Views.Dialogs.MessageBoxView"
+    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
+    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
+    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
+    xmlns:dialogs="clr-namespace:DiscordChatExporter.Gui.ViewModels.Dialogs"
+    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
+    xmlns:s="https://github.com/canton7/Stylet"
+    MinWidth="500"
+    d:DataContext="{d:DesignInstance Type=dialogs:MessageBoxViewModel}"
+    d:DesignHeight="450"
+    d:DesignWidth="800"
+    Style="{DynamicResource MaterialDesignRoot}"
+    mc:Ignorable="d">
+    <Grid>
+        <Grid.RowDefinitions>
+            <RowDefinition Height="Auto" />
+            <RowDefinition Height="*" />
+            <RowDefinition Height="Auto" />
+        </Grid.RowDefinitions>
+
+        <!--  Title  -->
+        <TextBlock
+            Grid.Row="0"
+            Margin="16"
+            FontSize="17"
+            Text="{Binding Title}"
+            TextTrimming="CharacterEllipsis"
+            ToolTip="{Binding Title}" />
+
+        <!--  Message  -->
+        <TextBlock
+            Grid.Row="1"
+            Margin="16,0,16,16"
+            Text="{Binding Message}"
+            TextWrapping="Wrap" />
+
+        <!--  Close  -->
+        <Button
+            Grid.Row="2"
+            Margin="8"
+            HorizontalAlignment="Right"
+            Command="{s:Action Close}"
+            Content="CLOSE"
+            IsCancel="True"
+            IsDefault="True"
+            Style="{DynamicResource MaterialDesignFlatButton}" />
+    </Grid>
+</UserControl>

DiscordChatExporter.Gui/Views/Dialogs/MessageBoxView.xaml.cs

@@ -0,0 +1,10 @@
+namespace DiscordChatExporter.Gui.Views.Dialogs
+{
+    public partial class MessageBoxView
+    {
+        public MessageBoxView()
+        {
+            InitializeComponent();
+        }
+    }
+}