Getting Error Type is not assignable

[gianluca1606]

Hello guys I am trying to get started to GraphQL and Nexus.

What have I done so far ?

I copied this example Prisma-GraphQL-Auth-Example

I extended the schema.prisma by creating three new models.

model Categories {
  id        Int      @id @default(autoincrement())
  createdAt DateTime @default(now())
  updatedAt DateTime @updatedAt
  title     String
  icon      String?
  Post      Post[]
}

model Comments {
  id        Int      @id @default(autoincrement())
  createdAt DateTime @default(now())
  updatedAt DateTime @updatedAt
  content   String?
  author    User?    @relation(fields: [authorId], references: [id])
  authorId  Int?
  post      Post?    @relation(fields: [postId], references: [id])
  postId    Int?
}

model Likes {
  id       Int     @id @default(autoincrement())
  thumbsup Boolean @default(false)
  user     User?   @relation(fields: [userId], references: [id])
  userId   Int?
}

I am trying to create the corresponding TypeDefs of my new models.
With the categories everything seems to be working fine.

But with the PostDef I have the issue mentioned in the title.

export const Post = objectType({
  name: 'Post',
  definition(t) {
    t.nonNull.int('id')
    t.nonNull.field('createdAt', { type: 'DateTime' })
    t.nonNull.field('updatedAt', { type: 'DateTime' })
    t.nonNull.string('title')
    t.string('content')
    t.nonNull.boolean('published')
    t.nonNull.int('viewCount')
    t.field('author', {
      type: 'User',
      resolve: (parent, _, context: Context) => {
        return context.prisma.post
          .findUnique({
            where: { id: parent.id || undefined },
          })
          .author()
      },
    })
    t.nonNull.field('Categories', {
      type: 'Categories',
      resolve: (parent, _, context: Context) => {
        return context.prisma.post
          .findUnique({
            where: { id: parent.id || undefined },
          })
          .Categories()
      },
    })
  },
})

The issue is related to the 'Categories' resolver:

Type '(parent: { content?: string | null | undefined; createdAt: any; id: number; published: boolean; title: string; updatedAt: any; viewCount: number; }, _: {}, context: Context) => Prisma__CategoriesClient<Categories | null>' is not assignable to type 'FieldResolver<"Post", "Categories">'.
  Type 'Prisma__CategoriesClient<Categories | null>' is not assignable to type '{ createdAt: any; icon: string; id: number; title: string; updatedAt: any; } | PromiseLike<{ createdAt: any; icon: string; id: number; title: string; updatedAt: any; }> | { createdAt: any; icon: MaybePromise<...>; id: MaybePromise<...>; title: MaybePromise<...>; updatedAt: any; } | PromiseLike<...>'.
    Type 'Prisma__CategoriesClient<Categories | null>' is not assignable to type 'PromiseLike<{ createdAt: any; icon: string; id: number; title: string; updatedAt: any; } | { createdAt: any; icon: MaybePromise<string>; id: MaybePromise<number>; title: MaybePromise<...>; updatedAt: any; }>'.
      Types of property 'then' are incompatible.
        Type '<TResult1 = Categories | null, TResult2 = never>(onfulfilled?: ((value: Categories | null) => TResult1 | PromiseLike<TResult1>) | null | undefined, onrejected?: ((reason: any) => TResult2 | PromiseLike<...>) | ... 1 more ... | undefined) => Promise<...>' is not assignable to type '<TResult1 = { createdAt: any; icon: string; id: number; title: string; updatedAt: any; } | { createdAt: any; icon: MaybePromise<string>; id: MaybePromise<number>; title: MaybePromise<string>; updatedAt: any; }, TResult2 = never>(onfulfilled?: ((value: { ...; } | { ...; }) => TResult1 | PromiseLike<...>) | ... 1 more...'.
          Types of parameters 'onfulfilled' and 'onfulfilled' are incompatible.
            Types of parameters 'value' and 'value' are incompatible.
              Type 'Categories | null' is not assignable to type '{ createdAt: any; icon: string; id: number; title: string; updatedAt: any; } | { createdAt: any; icon: MaybePromise<string>; id: MaybePromise<number>; title: MaybePromise<string>; updatedAt: any; }'.
                Type 'null' is not assignable to type '{ createdAt: any; icon: string; id: number; title: string; updatedAt: any; } | { createdAt: any; icon: MaybePromise<string>; id: MaybePromise<number>; title: MaybePromise<string>; updatedAt: any; }'.ts(2322)
definitionBlocks.d.ts(160, 5): The expected type comes from property 'resolve' which is declared here on type 'NexusOutputFieldConfig<"Post", "Categories"> & { resolve: FieldResolver<"Post", "Categories">; }' ```




Another question I have is, how can I split the queries and mutations?
In the graphql-auth example i linked above everything is inside the 'Query' objectType, the same for the 'Mutation'.

I would be very happy if someone could help me. Thanks in advance for your attention.