Converting an initial html content to ydoc with a NodeJS server and saving it in database does not work. about hocuspocus HOT 5 CLOSED

import * as dotenv from "dotenv";
dotenv.config();
import { Server } from "@hocuspocus/server";
import { Database } from "@hocuspocus/extension-database";
import StarterKit from "@tiptap/starter-kit";
import { TiptapTransformer } from "@hocuspocus/transformer";
import { generateJSON } from "@tiptap/html";
//import rethinkdb from "rethinkdb";
import Image from "@tiptap/extension-image";

import Table from "@tiptap/extension-table";
import TableCell from "@tiptap/extension-table-cell";
import TableHeader from "@tiptap/extension-table-header";
import TableRow from "@tiptap/extension-table-row";
import express from "express";
import * as Y from "yjs";
import { fromUint8Array, toUint8Array } from "js-base64";

const app = express();
const port = process.env.HOCUSPOCUS_API_PORT;
//const port = 3030;

const CustomTableCell = TableCell.extend({
	addAttributes() {
		return {
			// extend the existing attributes …
			...this.parent?.(),

			// and add a new one …
			backgroundColor: {
				default: null,
				parseHTML: (element) =>
					element.getAttribute("data-background-color"),
				renderHTML: (attributes) => {
					return {
						"data-background-color": attributes.backgroundColor,
						style: `background-color: ${attributes.backgroundColor}`,
					};
				},
			},
		};
	},
});

app.post("/transform", express.json(), (req, res) => {
	const room = req.body.room;
	const html = req.body.template_content;
	console.log("Received: " + room);
	try {
		const ydoc = TiptapTransformer.toYdoc(
			generateJSON(html, [
				StarterKit,
				Table.configure({
					resizable: true,
				}),
				TableRow,
				TableHeader,
				CustomTableCell,
				Image.configure({
					inline: true,
				}),
			]),
			"default",
			[
				StarterKit,
				Table.configure({
					resizable: true,
				}),
				TableRow,
				TableHeader,
				CustomTableCell,
				Image.configure({
					inline: true,
				}),
			]
		);
		const documentState = Y.encodeStateAsUpdate(ydoc);
		const base64Encoded = fromUint8Array(documentState);

		const responseData = {
			status: true,
			ydoc: base64Encoded,
		};
		console.log(responseData);
		res.setHeader("Content-Type", "application/json");
		res.json(responseData);
	} catch (error) {
		console.error(error);
		const responseData = {
			status: false,
			message: "An error occured while converting document.",
		};
		console.log(responseData);
		res.setHeader("Content-Type", "application/json");
		res.json(responseData);
	}
});

app.listen(port, () => {
	console.log(`Server is running on port:${port}`);
});

const html = req.body.template_content;
const ydoc = TiptapTransformer.toYdoc(
  generateJSON(html, [StarterKit]),
  "default",
  [StarterKit]);
const documentState = Y.encodeStateAsUpdate(ydoc);
const base64Encoded = fromUint8Array(documentState);

const ydoc = toUint8Array(base64Encoded);
return ydoc;