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Cannot find module 'graphql/validation/rules/PossibleTypeExtensions'

I'm in the process of learning about the MERN stack by following this book https://www.amazon.com/Pro-MERN-Stack-Development-Express-dp-1484243900/dp/1484243900/ref=mt_paperback?_encoding=UTF8&me=&qid= but even if it is a very recent one (published in 2019) the code examples are a travesty.

Basically when I try to start the server contained in this repo https://github.com/vasansr/pro-mern-stack-2/tree/05.02-graphql-schema-file with the command npm start the app crashes and it returns an

Error: Cannot find module 'graphql/validation/rules/PossibleTypeExtensions'

The code in the repo was published directly by the author so I don't exactly know how to solve this, could someone help me?