Update index.js

[Imran-imtiaz48]

Improvements:

1. React.StrictMode: Wraps the component tree to help identify potential issues during development.
2. Error Handling: Added a fallback if the root element is not found to avoid runtime errors.
3. Alias for BrowserRouter: Used Router alias for brevity and consistency.
4. Validation for Root Element: Ensures the root element exists before rendering.