Populate with TypeScript not working on Cursor

[schwarmco]

Prerequisites

• I have written a descriptive issue title
• I have searched existing issues to ensure the bug has not already been reported

Mongoose version

8.2.0

Node.js version

20.x

MongoDB server version

7.05

Typescript version (if applicable)

5.3.3

Description

Applying the Paths generic parameter as described in the mongoose documentation and fetching documents in a cursor does not result in the correct type.

Steps to Reproduce

import { Schema, model, Types } from 'mongoose'

// `Parent` represents the object as it is stored in MongoDB
interface Parent {
    child?: Types.ObjectId
    name?: string
}
const ParentModel = model<Parent>(
    'Parent',
    new Schema({
        child: { type: Schema.Types.ObjectId, ref: 'Child' },
        name: String
    })
)

interface Child {
    name: string
}
const childSchema: Schema = new Schema({ name: String })
const _ChildModel = model<Child>('Child', childSchema)

async function main() {
    // This works
    const result = await ParentModel.find({}).populate<{ child: Child }>('child').orFail()
    for (const doc of result) {
        const _t: string = doc.child.name
    }

    // This does not
    const cursor = ParentModel.find({}).populate<{ child: Child }>('child').cursor()
    for await (const doc of cursor) {
        const _t: string = doc.child.name // doc.child is Types.ObjectId
    }
}

Expected Behavior

The populated child should be of type Child as defined in the Paths generic parameter

[FaizBShah]

As far as I can see, there is population happening inside the cursor's next() function. I think the issue might be because of wrong type return I guess.

As is visible here, the cursor() function is returning Cursor of type DocType (which is the original parent type) instead of the ResultType (which is the type of the populated doc).

@vkarpov15 Is this intended? If this is a bug which can be fixed, I'll love to create a PR for this