![Screenshot 2019-12-16 10 51 05](https://user-images.githubusercontent.com/793565/70934095-fd91ed80-1ff1-11ea-93b5-746e816585ec.png)
There's seems to be circumstances where unmounted DOM/Fibers are kept alive by React DevTools. They're kept alive in `primaryFibers`:
https://github.com/facebook/react/blob/34527063083195558f98108cde10b5d6ad0d6865/packages/react-devtools-shared/src/backend/renderer.js#L772

It seems like a WeakSet would be appropriate and would remove the leak. Otherwise we'd need to understand why recordUnmount isn't called.

CC @bvaughn  
case 'hooks':
          if (path.length === 1) {
             N
            return true;
          }
          if (
            path[path.length - 2] === 'hookSource' &&
            path[path.length - 1] === 'fileName'
          ) {
             I
             i
             O
            return true;
          }
          if (
            path[path.length - 1] === 'subHooks' ||
            path[path.length - 2] === 'subHooks'
          ) {
             D
             s
             W
            return true;
          }
          break;
        default:
          break;
      }
      let current =
        key === null ? currentlyInspectedPaths : currentlyInspectedPaths[key];
      if (!current) {