JavaScript optional chaining dynamic property
You can create an interface that maps your theme object and pass the compiler type checking.
interface Headers { [key: string]: { [key: string]: string }}interface Theme { headers: Headers}const theme: Theme = { headers: { h1: { }, h6: { color: '#828286' }, },}console.info(theme?.headers?.['h6']?.color ?? '#000') //will passconsole.info(theme?.headers?.['h1']?.color ?? '#000')