[Bug?]: Upgrading Redwood to Canary causes "unmountComponentAtNode is not a function" in Storybook

[arimendelow]

What's not working?

If you update an existing Redwood project that was already using Storybook to Canary, and then try to start Storybook, you'll get this:

How do we reproduce the bug?

1. Run yarn create redwood-app test-upgrade-to-canary to make a nice new fresh project.
   • (At time of writing, this created a project based on Redwood 7.6.3)
2. Complete your project setup (yarn; yarn rw dev, etc).
3. Generate a test component: yarn rw g component test.
4. Optionally, run yarn rw sb and confirm that it works correctly at this stage.
5. Upgrade to canary by running yarn rw upgrade --tag "canary".
   • (At time of writing, upgraded to "8.0.0-canary.797")
6. Now, run yarn rw sb and note that you see the following:

Alternatively, if you create the new project as a canary (npx create-redwood-app@canary), you'll have no such issues.