DevTools: Crashes and warnings when quickly collapsing

This is weird. Happens if I select a node deeply and then long-press "left" arrow. ``` Invalid index 154 specified; store contains 154 items. Uncaught Invariant Violation: Expected to find a host parent. This error is likely caused by a bug in React. Please file an issue. at ReactError (file:///Users/gaearon/p/react-devtools-experimental/shells/dev/build/devtools.js:8529:40) ``` It starts with "invalid index" and then gives me different React invariants or warnings depending on how lucky I am.  --- More weird symptoms: <img width="889" alt="Screen Shot 2019-04-25 at 6 38 22 PM" src="https://user-images.githubusercontent.com/810438/56756281-5671f480-6789-11e9-8d0b-631a5217e63b.png"> --- <img width="832" alt="Screen Shot 2019-04-25 at 6 41 37 PM" src="https://user-images.githubusercontent.com/810438/56756492-c7191100-6789-11e9-8814-cb849590ee01.png"> --- This "fixes" it: ```diff runWithPriority(UserBlockingPriority, () => dispatch(action)); - next(() => dispatch({ type: 'UPDATE_INSPECTED_ELEMENT_ID' })); + runWithPriority(UserBlockingPriority, () => dispatch({ type: 'UPDATE_INSPECTED_ELEMENT_ID' })); }, ``` So I suspect it's a bug with `Scheduler.next()`. --- This also looks funky. Note how somewhere in the middle right pane gets "stuck" showing the same cycle of values:  --- React bug: https://github.com/facebook/react/issues/15512 --- Originally reported by @gaearon via https://github.com/bvaughn/react-devtools-experimental/issues/228