WebDriver: Do not ignore the result of closing a session

Author: https://github.com/trflynn89
Commit: 0ae015e266
Pull-request: https://github.com/SerenityOS/serenity/pull/17748
Reviewed-by: https://github.com/kalenikaliaksandr
Reviewed-by: https://github.com/linusg ✅

Userland/Services/WebDriver/Session.cpp

@@ -123,7 +123,7 @@ Web::WebDriver::Response Session::close_window()
 
     // 4. If there are no more open top-level browsing contexts, then close the session.
     if (m_windows.is_empty())
-        stop();
+        TRY(stop());
 
     // 5. Return the result of running the remote end steps for the Get Window Handles command.
     return get_window_handles();