It is possible to get in a state where loading the current layout of unity fails. When this happens the "Failed to load layout dialog" will popup. It is possible to get in a state where the 2 options in the dialog won't be able to restore your state. You might even get in an infinite loop of "revert to factory settings".

One suc occurences has been logged here: https://unity.slack.com/archives/CGJUHNZH7/p1603722679009800

Some use on the forum has logged a similar issue: https://forum.unity.com/threads/infinite-loop-on-failed-to-load-window-layout-revert-all-window-layouts.964940/

Another slack thread with more context on the bug: https://unity.slack.com/archives/C06TQ0QMQ/p1603442682393700

Basically:
- If loading the default layout throws an exception we should try loading a more stable layout?
- Revert to factory settings should be more radical: cleanup the current-mode-id preference, delete all layouts in User preference, delete the Library currentlayout.