Nested object type resolvers giving type error in GraphQL Nexus while works without any type system - next.js

Question

I am building a classroom app. While the resolver and schema works as expected without any type system, but with using nexus TS is complaining about the type errors.
I am using NextJs, Apollo Server, and graphql nexus
Currently I am using local db.ts file as database.
Should I not use nested object types? Or am I doing something wrong here?
Is there any other way of using relationships in graphql?
typescript
export const Class = objectType({
name: "Class",
definition(t) {
t.nonNull.id("id"),
t.nonNull.string("title"),
t.nonNull.url("imageUrl"),
t.nonNull.dateTime("createdAt"),
t.nonNull.string("instructorUserId");
t.field('instructor',{
type:UserProfile,
resolve(root,_args,ctx){
return ctx.db.UserProfile.find(user => user.id === root.instructorUserId)
}
})
},
});
Resolve method is giving me type errors.
Type '(root: { createdAt: any; id: string; imageUrl: any; instructorUserId: string; title: string; }, _args: {}, ctx: Context) => { id: string; name: string; email: string; phoneNumber: number; joinedAt: string; lastOnlineAt: string; profileImg: string; role: string; } | undefined' is not assignable to type 'FieldResolver<"Class", "instructor">'.
Type '{ id: string; name: string; email: string; phoneNumber: number; joinedAt: string; lastOnlineAt: string; profileImg: string; role: string; } | undefined' is not assignable to type 'MaybePromise<{ email: string; id: string; joinedAt: any; lastOnlineAt: any; name: string; phoneNumber?: number | null | undefined; profileImg: any; role: "BASIC" | "STUDENT" | "TEACHER" | "SUPERADMIN"; } | null>'.
Type 'undefined' is not assignable to type 'MaybePromise<{ email: string; id: string; joinedAt: any; lastOnlineAt: any; name: string; phoneNumber?: number | null | undefined; profileImg: any; role: "BASIC" | "STUDENT" | "TEACHER" | "SUPERADMIN"; } | null>'.
UserProfile
typescript
export const RoleEnum = enumType({
name: "Role",
members: ["BASIC", "STUDENT", "TEACHER", "SUPERADMIN"],
description: "Role of user",
});
export const UserProfile = objectType({
name: "UserProfile",
definition(t) {
t.nonNull.id("id"),
t.nonNull.string("name"),
t.nonNull.string("email"),
t.int("phoneNumber"),
t.nonNull.dateTime("joinedAt"),
t.nonNull.dateTime("lastOnlineAt"),
t.nonNull.url("profileImg"),
t.nonNull.field("role", {
type: "Role"
});
},
});
UserProfile Object in db
ts
{
id: "e9276605-aecd-460a-b5f1-f470d115ab60",
name: "Dahlia Grant",
email: "dahlia#gmail.com",
phoneNumber: 4665943805,
joinedAt: "2023-12-03T10:15:30Z",
lastOnlineAt: "2023-12-03T10:15:30Z",
profileImg: "http://unsplash.it/300/300?gravity=center",
role: "TEACHER",
},
Meanwhile plain graphql code is working along with nested object types
schema.graphql
type UserProfile {
id: String!
name: String!
email: String!
phoneNumber: Int
joinedAt: DateTime!
lastOnlineAt: DateTime!
profileImg: URL!
role: Role!
instructorInClasses: [Class!]!
posts: [Post!]!
likes: [PostLike!]!
classesEnrolled: [Class]!
}
type Class {
id: String!
title: String!
imageUrl: String
createdAt: DateTime!
instructor: UserProfile!
instructorUserId: String!
studentsEnrolled: [UserProfile!]!
posts: [Post!]!
}
Corresponding resolvers
ts
Class:{
instructor:(parent:Class,args:any,ctx:any) => {
const {instructorUserId} = parent
return db.UserProfile.find(user => user.id === instructorUserId)
},
studentsEnrolled:(parent:Class,args:any,ctx:any) => {
const {id} = parent
return db.StudentsEnrolled.filter(item => item.classId === id)
},
posts:(parent:Class,args:any,ctx:any) => {
const {id} = parent
return db.Post.filter(post => post.classId === id)
},
},
I tried removing nonNull but still the type error persisted.
Underlying Prisma schema that I am trying to implement
model UserProfile {
id String #id #default(uuid())
name String
email String #unique
phoneNumber Int? #unique
joinedAt DateTime #default(now())
lastOnlineAt DateTime #default(now())
role Role #default(BASIC)
instructorInClasses Class[] #relation(name: "ClassInstructor")
posts Post[] #relation(name: "PostedOwner")
likes PostLike[] #relation(name: "PostLiked")
classesEnrolled Class[]
}
model Class {
id String #id #default(uuid())
title String
imageUrl String #default("")
createdAt DateTime #default(now())
instructor UserProfile #relation(name: "ClassInstructor", fields: [instructorUserId], references: [id])
instructorUserId String
studentsEnrolled UserProfile[]
posts Post[] #relation(name: "ClassPost")
}
model Post {
id String #id #default(uuid())
title String
text String
views Int #default(0)
postType PostType #default(PUBLIC)
belongsToClass Class? #relation(name: "ClassPost", fields: [classId], references: [id])
classId String
createdAt DateTime #default(now())
updatedAt DateTime #updatedAt
postedBy UserProfile #relation(name: "PostedOwner", fields: [postedByUserId], references: [id])
postedByUserId String
postLikes PostLike[] #relation(name: "LikePostId")
}
model PostLike {
id String #id #default(uuid())
createdAt DateTime #default(now())
likedOnPost Post #relation(name: "LikePostId", fields: [postId], references: [id])
postId String
likedBy UserProfile #relation(name: "PostLiked", fields: [likedByUserId], references: [id])
likedByUserId String
}