Fix FocusScope missing parent element

[snowystinger]

Closes #3877

We're still trying to figure out what circumstances can lead to this, discussion in the issue. However, it's a safe enough guard. The first thing that focusFirstInScope will call is getScopeRoot, which may return null/undefined. Rather than blow up the application, we can just do nothing.

✅ Pull Request Checklist:

• Included link to corresponding React Spectrum GitHub Issue.
• Added/updated unit tests and storybook for this change (for new code or code which already has tests).
• Filled out test instructions.
• Updated documentation (if it already exists for this component).
• Looked at the Accessibility Practices for this feature - Aria Practices

📝 Test Instructions:

Unit tests pass, focus is normally contained in all existing stories

🧢 Your Project:

[filipw01]

I'm really happy we found the root cause

[rspbot]

Build successful! 🎉

• View the storybook
• View the storybook-17
• View the storybook-16
• View the documentation

[rspbot]

Build successful! 🎉

• View the storybook
• View the storybook-17
• View the storybook-16
• View the documentation

[rspbot]

## API Changes

unknown top level export { type: 'identifier', name: 'Column' }
unknown top level export { type: 'identifier', name: 'Column' }
unknown type { type: 'link' }
unknown type { type: 'link' }
unknown type { type: 'link' }
unknown type { type: 'link' }
unknown type { type: 'link' }
unknown type { type: 'link' }