Clean up and pop dead runspace when using 'attach' for V2 (#897)

* Clean up and pop dead runspace when using 'attach'

* named param

* big comment

Author: TylerLeonhardt

src/PowerShellEditorServices/Session/PowerShell5Operations.cs

@@ -85,7 +85,11 @@ public IEnumerable<TResult> ExecuteCommandInDebugger<TResult>(
 
         public void StopCommandInDebugger(PowerShellContext powerShellContext)
         {
-            powerShellContext.CurrentRunspace.Runspace.Debugger.StopProcessCommand();
+            // If the RunspaceAvailability is None, the runspace is dead and we should not try to run anything in it.
+            if (powerShellContext.CurrentRunspace.Runspace.RunspaceAvailability != RunspaceAvailability.None)
+            {
+                powerShellContext.CurrentRunspace.Runspace.Debugger.StopProcessCommand();
+            }
         }
 
         public void ExitNestedPrompt(PSHost host)

src/PowerShellEditorServices/Session/PowerShellContext.cs

@@ -765,10 +765,21 @@ public async Task<IEnumerable<TResult>> ExecuteCommandAsync<TResult>(
                         executionOptions,
                         true);
 
-                    throw e;
+                    throw;
                 }
                 finally
                 {
+                    // If the RunspaceAvailability is None, it means that the runspace we're in is dead.
+                    // If this is the case, we should abort the execution which will clean up the runspace
+                    // (and clean up the debugger) and then pop it off the stack.
+                    // An example of when this happens is when the "attach" debug config is used and the
+                    // process you're attached to dies randomly.
+                    if (this.CurrentRunspace.Runspace.RunspaceAvailability == RunspaceAvailability.None)
+                    {
+                        this.AbortExecution(shouldAbortDebugSession: true);
+                        this.PopRunspace();
+                    }
+
                     // Get the new prompt before releasing the runspace handle
                     if (executionOptions.WriteOutputToHost)
                     {