Debugger: Fix #14374.

ExpressionPromptWindow:
- Post a quit requested rather than quitting directly. As a consequence of
  this oversight, the team window would never get the notification that the
  prompt had been closed, and would consequently not reset its internal state
  properly.

src/apps/debugger/user_interface/gui/utility_windows/ExpressionPromptWindow.cpp

@@ -110,7 +110,7 @@ ExpressionPromptWindow::MessageReceived(BMessage* message)
 			addMessage.AddBool("persistent", true);
 
 			BMessenger(fAddTarget).SendMessage(&addMessage);
-			Quit();
+			PostMessage(B_QUIT_REQUESTED);
 			break;
 		}