sanity-algolia "Cannot read property 'created' of undefined" error in NextJS API

// sanity.blueprint.ts
import { defineBlueprint } from 'sanity'
import algoliasearch from 'algoliasearch'

const client = algoliasearch(
  process.env.ALGOLIA_APP_ID!,
  process.env.ALGOLIA_ADMIN_KEY!
)
const index = client.initIndex('your_index_name')

export default defineBlueprint({
  functions: {
    algoliaSync: {
      on: 'document.create,document.update,document.delete',
      filter: '_type in ["post", "page"]', // Specify your document types
      handler: async ({ event, sanityClient }) => {
        const { _id, operation } = event

        if (operation === 'delete') {
          await index.deleteObject(_id)
          return { success: true, action: 'deleted' }
        }

        // Fetch the full document with the fields you need
        const document = await sanityClient.fetch(
          `*[_id == $id][0]{
            objectID: _id,
            title,
            slug,
            content,
            // Add other fields you want to index
          }`,
          { id: _id }
        )

        if (document) {
          await index.saveObject(document)
          return { success: true, action: 'indexed' }
        }

        return { success: false, reason: 'document not found' }
      }
    }
  }
})

// pages/api/algolia-sync.js (or app/api/algolia-sync/route.ts for App Router)
import algoliasearch from 'algoliasearch'
import { createClient } from '@sanity/client'
import { isValidSignature, SIGNATURE_HEADER_NAME } from '@sanity/webhook'

const algolia = algoliasearch(
  process.env.ALGOLIA_APP_ID,
  process.env.ALGOLIA_ADMIN_KEY
)
const index = algolia.initIndex('your_index_name')

const sanityClient = createClient({
  projectId: process.env.NEXT_PUBLIC_SANITY_PROJECT_ID,
  dataset: process.env.NEXT_PUBLIC_SANITY_DATASET,
  apiVersion: '2024-01-01',
  useCdn: false
})

export default async function handler(req, res) {
  if (req.method !== 'POST') {
    return res.status(405).json({ message: 'Method not allowed' })
  }

  // Verify webhook signature
  const signature = req.headers[SIGNATURE_HEADER_NAME]
  const isValid = isValidSignature(
    JSON.stringify(req.body),
    signature,
    process.env.SANITY_WEBHOOK_SECRET
  )

  if (!isValid) {
    return res.status(401).json({ message: 'Invalid signature' })
  }

  try {
    const { _id, operation, value } = req.body

    // Handle delete operation
    if (operation === 'delete') {
      await index.deleteObject(_id)
      return res.status(200).json({ success: true, action: 'deleted' })
    }

    // For create/update, the value from the webhook projection contains the data
    if (value) {
      await index.saveObject(value)
      return res.status(200).json({ success: true, action: 'indexed' })
    }

    return res.status(400).json({ error: 'No value provided' })
  } catch (error) {
    console.error('Algolia sync error:', error)
    return res.status(500).json({ error: error.message })
  }
}

{
  "transactionId": _rev,
  "projectId": sanity::projectId(),
  "dataset": sanity::dataset(),
  _id,
  "operation": delta::operation(),
  "value": {
    "objectID": _id,
    "title": title,
    "slug": slug.current,
    "body": pt::text(content),
    "_type": _type,
    "coverImage": coverImage.asset->url,
    "date": date,
    "_createdAt": _createdAt,
    "_updatedAt": _updatedAt
  }
}