When supplying a default value for a required field, it is not used and instead throws a validation error. ```js const { graphql, buildSchema } = require('graphql') const schema = buildSchema(` type Query { hello(x: Int! = 42): Int } `) const root = { hello: (args) => args.x } graphql(schema, '{ hello }', root).then(console.log) ``` Produces: `GraphQLError: Field "hello" argument "x" of type "Int!" is required but not provided.`