Cannot read property 'collection' of null

First of all, let me thank you for this wonderful library. I finally finished migrating away a tree implementation (2 level only) from react-sortable-tree to this library, and it's been a revelation!

Having said that, there is a very occasional exception happening with this stack trace: https://sentry.io/share/issue/f56935f0904a46b99651022ca63791cd/

I cannot reproduce it, I only get it from Sentry.

// I guess isActive should be checked before getActive.