How to upload image file with useStorage('assets:something')

[VladimirCores]

Setting:

serverAssets: [{
  baseName: 'avatars',
  dir: '../public/upload/avatars', // Relative to `srcDir` (`server/` for nuxt)
}],

In dev (nuxt dev) mode I'm able to upload image in public folder:

import crypto from 'crypto';
import _ from 'lodash';

import StorageKeys from '~/server/constants/StorageKeys';

const isProd = process.env.NODE_ENV === 'production';

const FOLDER_PUBLIC = isProd ? 'assets/' : '/upload/';
const FOLDER_AVATARS = 'avatars';
const FOLDER_FINAL = `${FOLDER_PUBLIC}${FOLDER_AVATARS}`;

export default defineEventHandler(async(event) => {
  const body = await readMultipartFormData(event);

  const file = (body! as any[]).shift();
  const [type, ext] = file.type.split('/');

  const fileName = `${crypto.randomUUID()}.${ext}`;
  const filePath = `${FOLDER_FINAL}/${fileName}`;

  const assetsStorage = useStorage('assets:avatars');

  console.log('> fileName =', fileName);
  console.log('> filePath =', filePath);

  assetsStorage.setItemRaw(fileName, file.data);

  return filePath;
});

And it works in dev mode.

But after build (nuxt build) and run (node .output/server/index.mjs) nothing works.

Please help to find out how store files in prod?