Vercel app with graphql-codegen endpoint error Unable to find any GraphQL type definitions for the following pointers

I load my GraphQL schema like:

const schema = loadSchemaSync('./src/graphql/server/schema/*.gql', {
  loaders: [new GraphQLFileLoader()],
})

This works fine locally, however, when deploying to vercel I get the error:

Unable to find any GraphQL type definitions for the following pointers:
          - ./src/graphql/server/schema/*.gql

I think this is because vercel is dropping the relevant files after build?