Surface fire-and-forget command failures immediately

Commands and context-menu entries kick off async work as `_ = SomeAsync()`,
discarding the task. When one faulted, the failure only surfaced via
TaskScheduler.UnobservedTaskException after the GC finalized the dropped
task -- late, on the finalizer thread, and disconnected from the gesture
that caused it (a click would appear to do nothing, then a mysterious
crash report arrived seconds later).

Add a HandleExceptions() extension that observes such a task on the UI
context and routes any fault to the existing GlobalExceptionHandler at
the point of failure (treating cancellation as a normal outcome), and
route the user-invoked command/entry sites through it. The global
unhandled-exception net already existed; this just makes these failures
prompt and attributable instead of deferred to GC.

Assisted-by: Claude:claude-opus-4-8:Claude Code

ILSpy/Commands/CreateDiagramContextMenuEntry.cs

@@ -66,7 +66,7 @@ namespace ILSpy.Commands
 			var assembly = (context.SelectedTreeNodes?.FirstOrDefault() as AssemblyTreeNode)?.LoadedAssembly;
 			if (assembly == null)
 				return;
-			_ = ExecuteAsync(assembly.FileName);
+			ExecuteAsync(assembly.FileName).HandleExceptions();
 		}
 
 		async Task ExecuteAsync(string assemblyFile)

ILSpy/Commands/DecompileAllCommand.cs

@@ -61,7 +61,7 @@ namespace ILSpy.Commands
 
 		public override bool CanExecute(object? parameter) => Directory.Exists(OutputDir);
 
-		public override void Execute(object? parameter) => _ = ExecuteAsync();
+		public override void Execute(object? parameter) => ExecuteAsync().HandleExceptions();
 
 		async Task ExecuteAsync()
 		{
@@ -132,7 +132,7 @@ namespace ILSpy.Commands
 
 		public override bool CanExecute(object? parameter) => Directory.Exists(OutputDir);
 
-		public override void Execute(object? parameter) => _ = ExecuteAsync();
+		public override void Execute(object? parameter) => ExecuteAsync().HandleExceptions();
 
 		async Task ExecuteAsync()
 		{
@@ -203,7 +203,7 @@ namespace ILSpy.Commands
 			this.dockWorkspace = dockWorkspace;
 		}
 
-		public override void Execute(object? parameter) => _ = ExecuteAsync();
+		public override void Execute(object? parameter) => ExecuteAsync().HandleExceptions();
 
 		async Task ExecuteAsync()
 		{

ILSpy/Commands/ExportProjectContextMenuEntry.cs

@@ -57,8 +57,8 @@ namespace ILSpy.Commands
 		{
 			if (!ProjectExport.TryGetExportableAssemblies(context.SelectedTreeNodes, out var assemblies, out var solutionMode))
 				return;
-			_ = ProjectExport.PromptAndExportAsync(assemblies, solutionMode,
-				languageService.CurrentLanguage, dockWorkspace, settingsService);
+			ProjectExport.PromptAndExportAsync(assemblies, solutionMode,
+				languageService.CurrentLanguage, dockWorkspace, settingsService).HandleExceptions();
 		}
 	}
 }

ILSpy/Commands/ExtractPackageEntryContextMenuEntry.cs

@@ -73,7 +73,7 @@ namespace ILSpy.Commands
 				.FirstOrDefault(asm => asm.PackageEntry == null);
 			if (bundleNode == null)
 				return;
-			_ = ExecuteAsync(selectedNodes);
+			ExecuteAsync(selectedNodes).HandleExceptions();
 		}
 
 		async Task ExecuteAsync(SharpTreeNode[] selectedNodes)
@@ -267,7 +267,7 @@ namespace ILSpy.Commands
 		{
 			if (context.SelectedTreeNodes is not [AssemblyTreeNode { PackageEntry: null } asm])
 				return;
-			_ = ExecuteAsync(asm);
+			ExecuteAsync(asm).HandleExceptions();
 		}
 
 		async Task ExecuteAsync(AssemblyTreeNode asm)

ILSpy/Commands/FileCommands.cs

@@ -110,7 +110,7 @@ namespace ILSpy.Commands
 				as global::Avalonia.Controls.ApplicationLifetimes.IClassicDesktopStyleApplicationLifetime)?.MainWindow;
 			if (owner == null)
 				return;
-			_ = ShowAsync(owner);
+			ShowAsync(owner).HandleExceptions();
 		}
 
 		async System.Threading.Tasks.Task ShowAsync(global::Avalonia.Controls.Window owner)
@@ -300,8 +300,8 @@ namespace ILSpy.Commands
 		{
 			if (!ProjectExport.TryGetExportableAssemblies(assemblyTreeModel.SelectedItems, out var assemblies, out var solutionMode))
 				return;
-			_ = ProjectExport.PromptAndExportAsync(assemblies, solutionMode,
-				languageService.CurrentLanguage, dockWorkspace, settingsService);
+			ProjectExport.PromptAndExportAsync(assemblies, solutionMode,
+				languageService.CurrentLanguage, dockWorkspace, settingsService).HandleExceptions();
 		}
 	}
 

ILSpy/Commands/GeneratePdbContextMenuEntry.cs

@@ -69,7 +69,7 @@ namespace ILSpy.Commands
 			var selectedNodes = context.SelectedTreeNodes?.OfType<AssemblyTreeNode>().ToArray();
 			if (selectedNodes == null || selectedNodes.Length == 0)
 				return;
-			_ = ExecuteAsync(selectedNodes.Select(n => n.LoadedAssembly).ToArray());
+			ExecuteAsync(selectedNodes.Select(n => n.LoadedAssembly).ToArray()).HandleExceptions();
 		}
 
 		async Task ExecuteAsync(LoadedAssembly[] assemblies)

ILSpy/Commands/HelpCommands.cs

@@ -39,6 +39,6 @@ namespace ILSpy.Commands
 		// Force-checks regardless of the 7-day throttle and surfaces the result in the panel,
 		// including an explicit "up to date" banner when no newer version is found.
 		public override void Execute(object? parameter)
-			=> _ = updatePanel.CheckIfUpdatesAvailableAsync(notifyOnUpToDate: true);
+			=> updatePanel.CheckIfUpdatesAvailableAsync(notifyOnUpToDate: true).HandleExceptions();
 	}
 }

ILSpy/Commands/Pdb2XmlCommand.cs

@@ -66,7 +66,7 @@ namespace ILSpy.Commands
 			var nodes = assemblyTreeModel.SelectedItems.OfType<AssemblyTreeNode>().ToArray();
 			if (nodes.Length == 0)
 				return;
-			_ = ExecuteAsync(nodes);
+			ExecuteAsync(nodes).HandleExceptions();
 		}
 
 		async Task ExecuteAsync(AssemblyTreeNode[] nodes)

ILSpy/Commands/SaveCodeContextMenuEntry.cs

@@ -64,7 +64,7 @@ namespace ILSpy.Commands
 
 			if (SolutionExport.TryGetAssemblies(nodes, out var assemblies))
 			{
-				_ = SolutionExport.PromptAndExportAsync(assemblies, languageService.CurrentLanguage, dockWorkspace);
+				SolutionExport.PromptAndExportAsync(assemblies, languageService.CurrentLanguage, dockWorkspace).HandleExceptions();
 				return;
 			}
 

ILSpy/Commands/SelectPdbContextMenuEntry.cs

@@ -61,7 +61,7 @@ namespace ILSpy.Commands
 			var assembly = (context.SelectedTreeNodes?.FirstOrDefault() as AssemblyTreeNode)?.LoadedAssembly;
 			if (assembly == null)
 				return;
-			_ = ExecuteAsync(assembly);
+			ExecuteAsync(assembly).HandleExceptions();
 		}
 
 		async Task ExecuteAsync(ICSharpCode.ILSpyX.LoadedAssembly assembly)

ILSpy/FireAndForgetExtensions.cs

@@ -0,0 +1,55 @@
+// Copyright (c) 2026 AlphaSierraPapa for the SharpDevelop Team
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy of this
+// software and associated documentation files (the "Software"), to deal in the Software
+// without restriction, including without limitation the rights to use, copy, modify, merge,
+// publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons
+// to whom the Software is furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in all copies or
+// substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
+// INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR
+// PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE
+// FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
+// OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+// DEALINGS IN THE SOFTWARE.
+
+using System;
+using System.Threading.Tasks;
+
+using ILSpy.AppEnv;
+
+namespace ILSpy
+{
+	public static class FireAndForgetExtensions
+	{
+		/// <summary>
+		/// Observes a fire-and-forget task started from a command or event handler. Awaits it on the
+		/// captured (UI) context and routes any failure to <see cref="GlobalExceptionHandler"/>
+		/// immediately, at the point of failure. Without this, a discarded faulted task
+		/// (<c>_ = SomethingAsync()</c>) only surfaces via
+		/// <see cref="TaskScheduler.UnobservedTaskException"/> after the GC finalizes it — late, on
+		/// the finalizer thread, and disconnected from the gesture that triggered it.
+		/// <see cref="OperationCanceledException"/> is treated as a normal cooperative cancel, not an
+		/// error.
+		/// </summary>
+		public static async void HandleExceptions(this Task task)
+		{
+			ArgumentNullException.ThrowIfNull(task);
+			try
+			{
+				await task.ConfigureAwait(true);
+			}
+			catch (OperationCanceledException)
+			{
+				// Cooperative cancellation is an expected outcome, not a failure.
+			}
+			catch (Exception ex)
+			{
+				GlobalExceptionHandler.Show(ex);
+			}
+		}
+	}
+}

ILSpy/TreeNodes/AssemblyTreeNode.cs

@@ -161,7 +161,7 @@ namespace ILSpy.TreeNodes
 			var language = languageService.CurrentLanguage;
 			if (string.IsNullOrEmpty(language.ProjectFileExtension))
 				return false;
-			_ = SaveAsProjectOrSingleFileAsync(language);
+			SaveAsProjectOrSingleFileAsync(language).HandleExceptions();
 			return true;
 		}
 

ILSpy/TreeNodes/ImageListResourceEntryNode.cs

@@ -179,7 +179,7 @@ namespace ILSpy.ImageList
 
 		public override bool Save()
 		{
-			_ = SaveAsync();
+			SaveAsync().HandleExceptions();
 			return true;
 		}
 

ILSpy/TreeNodes/ResourceEntryNode.cs

@@ -67,7 +67,7 @@ namespace ILSpy.TreeNodes
 
 		public override bool Save()
 		{
-			_ = SaveAsync();
+			SaveAsync().HandleExceptions();
 			return true;
 		}
 

ILSpy/TreeNodes/ResourceTreeNode.cs

@@ -66,7 +66,7 @@ namespace ILSpy.TreeNodes
 
 		public override bool Save()
 		{
-			_ = SaveAsync();
+			SaveAsync().HandleExceptions();
 			return true;
 		}
 

ILSpy/TreeNodes/ResourcesFileTreeNode.cs

@@ -134,7 +134,7 @@ namespace ILSpy.TreeNodes
 
 		public override bool Save()
 		{
-			_ = SaveDialogAsync();
+			SaveDialogAsync().HandleExceptions();
 			return true;
 		}