Async resolve functions do not throw errors if they return undefined

[jer-sen]

When allowUndefinedInResolve === false, a resolver should throw an error if it returns undefined. But with an async resolver, no error is thrown.

apollo-server-lambda@2.13.1

[glasser]

This option is a parameter to makeExecutableSchema, a function that used to be part of Apollo Server but now is part of the separate graphql-tools project.

Additionally, it looks like this option was removed from graphql-tools last year (not mentioned in PR description but it's in the diff).