STRs: - Undock devtools - close/open devtools repeatedly (and quickly) After a few tries, DevTools will no longer open. Closing a docked toolbox seems to wait until DevTools are fully initialized. But closing devtools in a separate window is almost instantaneous and can interrupt the initialization of DevTools. Consequently it's really easy to break the destroy of the toolbox, by hitting codepaths that expect some objects to be defined etc... Either we need to heavily guard the destroy sequence, or we need to wait until devtools are initialized before allowing the window to be closed (maybe this is not possible though).

Assuming we're okay to slow down toolbox closing a bit, I would recommend making destroy wait on init to complete before starting. This has a few advantages: 1. destroy path is cleaner and easier to reason about 2. You know for sure that nothing else is starting up: without it, you might finish a guarded destroy and then have things continue starting up which then never get destroyed I encountered similar issues with RDM, though it takes different paths based on tab close vs. RDM close. Alternatively, we could try to investigate precisely what global state outside of toolbox itself ends up failing to allow a new toolbox to open, as you would assume that should never fail.