If an SQL error occurs in a mutation, previous data may still be rendered

[benjie]

For example if you perform createUser1, mutationThatProducesError, createUser2; the response may contain { createUser1: { id: 1, name: ... }, mutationThatProducesError: null, createUser2: null}; however the details of user 1 will have been rolled back by the mutation and thus should not be displayed to the user.

I suspect the solution is to use transaction checkpoints, because GraphQL will resolve each mutation field to completion before executing the next mutation field we don't need to worry about errors thrown in later mutations causing issues for resolve values of earlier mutation fields.