1. Apply this patch https://codereview.qt-project.org/c/qt-creator/qt-creator/+/347452
2. Load creator project into creator
3. As soon as you see the "Shutdown now" printout, close creator. It should crash.
The reason is that ClangEditorDocumentProcessor::runImpl() cancels the last future and sets the new one (m_parserWatcher), so the old one may still be running if the shutdown comes now.