How to Fetch Nested Entry or Reference Entry in Contentful? Cannot read property ‘fields’ of undefined

The short is in below screenshot

For more clarity watch the full video

I got this error while I was working with React and contentful singerProfile project github code link: https://github.com/Alidhuniya/singerProfile-ReactJS-with-Contentful

Contentful community forum: https://rb.gy/zpz36w