Yup schema won't add 'nullable' to optional fields.

When I run the generator, my Yup schema does not add .nullish() to any optional fields.

my-type.ts

@InputType
export class MyTypeInput {

  @Field(() => String)
  @IsString()
  @IsDefined()
  name!: string;

  @Field(() => ID, { nullable: true })
  @IsString()
  @IsOptional()
  imageId?: string;
}

schema.graphql

input MyTypeInput {
  name: String!
  imageId: ID
}

generated-operations.ts

export type MyTypeInput = {
  imageId?: InputMaybe<Scalars['ID']>;
  name: Scalars['String'];
}

Expected Result

generated-validation-schema.ts

export function MyTypeInputSchema(): yup.SchemaOf<MyTypeInput> {
  return yup.object({
    imageId: yup.string().nullable(),  // <----- this `nullable` is missing in the actual, below
    name: yup.string().defined()
  })
}

Actual Result

generated-validation-schema.ts

export function MyTypeInputSchema(): yup.SchemaOf<MyTypeInput> {
  return yup.object({
    imageId: yup.string(),
    name: yup.string().defined()
  })
}