Error: [!] (plugin babel) Error: You have declared using "bundled" babelHelpers, but transforming main.js resulted in "runtime"

I'm trying to bundle a javascript file using rollup but facing the following error:

[!] (plugin babel) Error: You have declared using "bundled" babelHelpers, but transforming main.js resulted in "runtime". Please check your configuration.

Following is the rollup.config.js file:

import resolve from '@rollup/plugin-node-resolve';
import replace from '@rollup/plugin-replace';
import { terser } from 'rollup-plugin-terser';
import { version } from './package.json';
import sourcemaps from 'rollup-plugin-sourcemaps';
import babel from '@rollup/plugin-babel';

export default {
  input: 'src/webSDK/main.js',
  output: [
    {
      name: 'SDK',
      file: 'public/jsSdk/app.js',
      format: 'umd',
      sourcemap: true,
    },
    {
      name: 'SDK',
      file: 'public/jsSdk/app.min.js',
      format: 'umd',
      plugins: [terser()],
    },
  ],
  plugins: [
    resolve(),
    sourcemaps(),
    replace({
      preventAssignment: true,
      delimiters: ['', ''],
      $$PACKAGE_VERSION$$: version,
    }),
    babel({
      babelHelpers: 'bundled',
    }),
  ],
};

Contents of main.js

import SDK from './app';

const webSdk = SDK;

window.webSdk = window.wizrocket = webSdk;

export default webSdk;