Extensions: don't swallow exceptions

I was tricked into thinking un-handled exceptions didn't result in a
non-zero exit code because of a Visual Studio debugger quirk. The
debugger's console window says "exited with code 0," but it lies!

UseExceptionHandler() is available for consumers who want to avoid hard
crashes.

fixes #5

XO.Console.Cli.Extensions/CommandAppHostBuilderExtensions.cs

@@ -73,18 +73,10 @@ internal static async Task<int> RunCommandAppAsync(
         hostBuilder.ConfigureServices(
             (_, services) => services.AddCommandApp(builderFactory, configure));
 
-        IHost host;
-        try
-        {
-            host = hostBuilder.Build();
-        }
-        catch (Exception ex)
-        {
-            System.Console.Error.WriteLine(ex.Message);
-            return -1;
-        }
+        // build the host
+        using var host = hostBuilder.Build();
 
-        // get a reference to the logger factory
+        // get a reference to the logger factory so we can dispose it last
         var loggerFactory = host.Services.GetService<ILoggerFactory>();
 
         // run the host
@@ -94,11 +86,6 @@ internal static async Task<int> RunCommandAppAsync(
             result = await host.RunCommandAppAsync(args)
                 .ConfigureAwait(false);
         }
-        catch (Exception ex)
-        {
-            System.Console.Error.WriteLine(ex.Message);
-            result = -1;
-        }
         finally
         {
             await DisposeAndFlush(host, loggerFactory)
@@ -118,11 +105,6 @@ private static ValueTask DisposeAndFlush(IHost host, ILoggerFactory? loggerFacto
             host.Dispose();
             return ValueTask.CompletedTask;
         }
-        catch (Exception ex)
-        {
-            System.Diagnostics.Debug.WriteLine(ex.ToString());
-            return ValueTask.CompletedTask;
-        }
         finally
         {
             loggerFactory?.Dispose();

XO.Console.Cli.Extensions/CommandAppHostExtensions.cs

@@ -42,17 +42,14 @@ public static async Task<int> RunCommandAppAsync(this IHost host, IReadOnlyList<
             try
             {
                 logger?.LogDebug("Executing command {Command} ... ", from x in parse.GetVerbs() select x.Value);
-                logger?.LogTrace("Command args: {Args}", args);
 
                 result = await app.ExecuteAsync(parse, lifetime.ApplicationStopping)
                     .ConfigureAwait(false);
             }
             catch (Exception ex)
             {
-                logger?.LogCritical(ex, "Unhandled exception: {ExceptionMessage}", ex.Message);
-
-                System.Console.Error.WriteLine(ex.Message);
-                result = 1;
+                logger?.LogCritical(ex, "An unhandled exception occurred while executing the command.");
+                throw;
             }
             finally
             {