Hide artificial pipeline from debugger

Same fix as applied in PowerShell/PSReadLine#3629

Author: andyleejordan

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

@@ -1207,7 +1207,18 @@ private Runspace CreateInitialRunspace(InitialSessionState initialSessionState)
             return runspace;
         }
 
-        // NOTE: This token is received from PSReadLine, and it _is_ the ReadKey cancellation token!
+        /// <summary>
+        /// This delegate is handed to PSReadLine and overrides similar logic within its `ReadKey`
+        /// method. Essentially we're replacing PowerShell's `OnIdle` handler since the PowerShell
+        /// engine isn't idle when we're sitting in PSReadLine's `ReadKey` loop. In our case we also
+        /// use this idle time to process queued tasks by executing those that can run in the
+        /// background, and canceling the foreground task if a queued tasks requires the foreground.
+        /// Finally, if and only if we have to, we run an artificial pipeline to force PowerShell's
+        /// own event processing.
+        /// </summary>
+        /// <param name="idleCancellationToken">
+        /// This token is received from PSReadLine, and it is the ReadKey cancellation token!
+        /// </param>
         internal void OnPowerShellIdle(CancellationToken idleCancellationToken)
         {
             IReadOnlyList<PSEventSubscriber> eventSubscribers = _mainRunspaceEngineIntrinsics.Events.Subscribers;
@@ -1257,10 +1268,15 @@ internal void OnPowerShellIdle(CancellationToken idleCancellationToken)
 
             // We didn't end up executing anything in the background,
             // so we need to run a small artificial pipeline instead
-            // to force event processing
+            // to force event processing.
             if (runPipelineForEventProcessing)
             {
-                InvokePSCommand(new PSCommand().AddScript("0", useLocalScope: true), executionOptions: null, CancellationToken.None);
+                InvokePSCommand(
+                    new PSCommand().AddScript(
+                        "[System.Diagnostics.DebuggerHidden()]param() 0",
+                        useLocalScope: true),
+                    executionOptions: null,
+                    CancellationToken.None);
             }
         }