Creating new mutations

This is hopefully super simple for someone who knows what they are doing, but I am new to both GraphQL and to RedwoodJS, so not for me

I have my generated model called Block. I would like to have the ability to delete multiple blocks at one time in a deleteBlocks function in the blocks service. I start by adding to the SDL Mutation:
deleteBlocks(ids: [String]!): Prisma.BatchPayload @requireAuth
When I go to create the function in the service, I am going to need an updated MutationResolvers type (I am using Typescript). How do I get that? I assume graphql.d.ts is auto-generated, so after adding that line to the SDL, I run yarn rw g types and get an error about unknown type ‘Block’

My question is, what is the process for adding new service functions and mutation definitions? Thanks!