Unexpected errors can occur when resolvers.js is loaded as part of the deploy process.
For example, it's common to create things like DB connections outside of the handler so that they persist as long as the lambda is running without being recreated on each call. Another thing that I'm experiencing is that I instrument my lambdas with aws xray and that loads and instruments http which can errors.
If this require was replaced with a fs read file and it was parsed differently it would still be possible to determine the keys under Query and Mutation.