Fix startup bug when zero profiles are present (#1807)

The service would fail to fully start if zero profiles were present,
because that meant we attempted to invoke an empty command, which then
threw `PSInvalidOperationException: No commands are specified`. This
wasn't caught by our task executor, since it happened in a delegate
which directly invoked the command.

Author: andyleejordan

src/PowerShellEditorServices/Services/PowerShell/Host/PsesInternalHost.cs

@@ -113,12 +113,12 @@ public PsesInternalHost(
             _cancellationContext = new CancellationContext();
 
             // Default stack size on .NET Framework is 524288 (512KB) (as reported by GetProcessDefaultStackSize)
-            // this leaves very little room in the stack. Windows PowerShell internally sets the value based on 
-            // PipelineMaxStackSizeMB as seen here: https://github.com/PowerShell/PowerShell/issues/1187, 
+            // this leaves very little room in the stack. Windows PowerShell internally sets the value based on
+            // PipelineMaxStackSizeMB as seen here: https://github.com/PowerShell/PowerShell/issues/1187,
             // which has default of 10 and multiplies that by 1_000_000, so the default stack size is
-            // 10_000_000 (~10MB) when starting in normal console host. 
+            // 10_000_000 (~10MB) when starting in normal console host.
             //
-            // For PS7 the value is ignored by .NET because settings the stack size is not supported, but we can 
+            // For PS7 the value is ignored by .NET because settings the stack size is not supported, but we can
             // still provide 0, which means fallback to the default in both .NET and .NET Framework.
             int maxStackSize = VersionUtils.IsPS5 ? 10_000_000 : 0;
             _pipelineThread = new Thread(Run, maxStackSize)
@@ -433,7 +433,7 @@ internal Task LoadHostProfilesAsync(CancellationToken cancellationToken)
             // NOTE: This is a special task run on startup!
             return ExecuteDelegateAsync(
                 "LoadProfiles",
-                new PowerShellExecutionOptions { ThrowOnError = false },
+                executionOptions: null,
                 (pwsh, _) => pwsh.LoadProfiles(_hostInfo.ProfilePaths),
                 cancellationToken);
         }

src/PowerShellEditorServices/Services/PowerShell/Utility/PowerShellExtensions.cs

@@ -2,13 +2,13 @@
 // Licensed under the MIT License.
 
 using System;
+using System.Collections.Generic;
 using System.Collections.ObjectModel;
 using System.Reflection;
 using System.Text;
 using Microsoft.Extensions.Logging;
 using Microsoft.PowerShell.EditorServices.Hosting;
 using Microsoft.PowerShell.EditorServices.Utility;
-using System.Collections.Generic;
 
 namespace Microsoft.PowerShell.EditorServices.Services.PowerShell.Utility
 {
@@ -211,7 +211,13 @@ public static void LoadProfiles(this PowerShell pwsh, ProfilePathInfo profilePat
             // NOTE: This must be set before the profiles are loaded.
             pwsh.Runspace.SessionStateProxy.SetVariable("PROFILE", profileVariable);
 
-            pwsh.InvokeCommand(psCommand);
+            // NOTE: Because it's possible there are no profiles defined, we might have an empty
+            // command. Since this is being executed directly, we can't rely on `ThrowOnError =
+            // false` to avoid an exception here. Instead, we must just not execute it.
+            if (psCommand.Commands.Count > 0)
+            {
+                pwsh.InvokeCommand(psCommand);
+            }
         }
 
         public static void ImportModule(this PowerShell pwsh, string moduleNameOrPath)

src/PowerShellEditorServices/Utility/PSCommandExtensions.cs

@@ -77,10 +77,7 @@ public static PSCommand AddProfileLoadIfExists(this PSCommand psCommand, PSObjec
 
             if (File.Exists(profilePath))
             {
-                psCommand
-                    .AddCommand(profilePath, useLocalScope: false)
-                    .AddOutputCommand()
-                    .AddStatement();
+                psCommand.AddCommand(profilePath, useLocalScope: false).AddOutputCommand().AddStatement();
             }
 
             return psCommand;