FocusScope broken in React 18 StrictMode

[RubenStoesser]

🐛 Bug Report

The last update (v3.8.0) to @react-aria/focus has introduced code that breaks FocusScope when running in React 18 StrictMode.

Rendering a <FocusScope throws this error:

Cannot set properties of undefined (setting 'nodeToRestore')

The issue does not occur when StrictMode is not enabled or v3.7.0 of @react-aria/focus is used.

🤔 Expected Behavior

FocusScope should not throw an error when rendering.

😯 Current Behavior

Whenever a FocusScope is rendered in StrictMode an error is thrown:

Cannot set properties of undefined (setting 'nodeToRestore')

The error seems to be thrown when trying to assign focusScopeTree.getTreeNode(scopeRef).nodeToRestore in this useLayoutEffect:

react-spectrum/packages/@react-aria/focus/src/FocusScope.tsx

Line 456 in 2411012

useLayoutEffect(() => {

💻 Code Sample

Example Code Sandbox using the example code from react-aria docs:

https://codesandbox.io/s/react-spectrum-template-forked-88lk5n?file=/src/App.js

To reproduce just click on the "open" button.

Note that when <StrictMode> is removed in the index.js file the error does not occur.
When the version of @react-aria/focus is changed to 3.7.0 the error also does not occur.

🌍 Your Environment

Software	Version(s)
@react-aria/focus	3.8.0
Browser	Chrome 104.0.5112.101
Operating System	MacOS 12.5.1

[reidbarber]

Thanks for finding! We have an umbrella issue for strict mode issues at #779, so I'll close this in favor of that.