fix(useFullscreen):accept nullable ref and add minimal test

[Ritinpaul]

Fixes #2662

Overview

This PR fixes a type-safety issue in useFullscreen and adds a minimal test to ensure basic functionality.

Description

useFullscreen currently expects RefObject<HTMLElement> which is not compatible with React's useRef/createRef that can be null. This PR changes the type to RefObject<HTMLElement | null>. Also added a small cast in the catch block for better TypeScript safety.

Type of change

• src/useFullscreen.ts:
  • Type change for ref parameter
  • Cast caught error to Error (onClose(error as Error))
• tests/useFullscreen.test.ts:
  • Minimal test to ensure the hook is defined and returns a boolean

Checklist

• Read the Contributing Guide
• Perform a code self-review
• Comment the code, particularly in hard-to-understand areas
• Add documentation
• Add hook's story at Storybook
• Cover changes with tests
• Ensure the test suite passes (yarn test)
• Provide 100% tests coverage
• Make sure code lints (yarn lint). Fix it with yarn lint:fix in case of failure.
• Make sure types are fine (yarn lint:types).