Unwanted "Es Module" story added to each story

[denvash]

Describe the bug
Es Module story was added for each of my stories.

To Reproduce
Steps to reproduce the behavior:

1. Run storybook yarn storybook
2. Check each story

Expected behavior
Es Module won't appear

Screenshots

Stories tabs

Es Module story

Code snippets

// @config.js
import React, { useContext } from 'react';
import { configure, addParameters, addDecorator } from '@storybook/react';
import { themes } from '@storybook/theming';
import { radios, withKnobs } from '@storybook/addon-knobs';
import { ThemeContext } from 'styled-components';

import GlobalStyle from '../src/styles/GlobalStyle.styles';
import ThemeProvider from '../src/components/ThemeProvider';
import theme from '../src/styles/theme';

const reducer = (acc, { name }, i) => {
  acc[name] = String(i);
  return acc;
};

const label = 'Themes';
const options = theme.palettes.reduce(reducer, {});
const defaultValue = Object.values(options)[0];

const Container = ({ children }) => {
  const controlledIndex = radios(label, options, defaultValue);
  const { setIndex } = useContext(ThemeContext);
  setIndex(Number(controlledIndex));
  return <>{children}</>;
};

addDecorator(withKnobs);
addDecorator(S => (
  <ThemeProvider>
    <Container>
      <GlobalStyle />
      <S />
    </Container>
  </ThemeProvider>
));

addParameters({
  options: {
    panelPosition: 'bottom',
    storySort: (a, b) => a[1].id.localeCompare(b[1].id),
    theme: themes.dark,
  },
});

System:

Environment Info:

  System:
    OS: Linux 4.15 Ubuntu 18.04.3 LTS (Bionic Beaver)
    CPU: (8) x64 Intel(R) Core(TM) i7-6700 CPU @ 3.40GHz
  Binaries:
    Node: 12.10.0 - /usr/local/bin/node
    Yarn: 1.19.1 - /usr/bin/yarn
    npm: 6.10.3 - /usr/local/bin/npm
  Browsers:
    Chrome: 77.0.3865.120
    Firefox: 69.0.2
  npmPackages:
    @storybook/addon-actions: ^5.2.3 => 5.2.3 
    @storybook/addon-knobs: ^5.2.3 => 5.2.3 
    @storybook/addon-links: ^5.2.3 => 5.2.3 
    @storybook/addon-viewport: ^5.2.3 => 5.2.3 
    @storybook/addons: ^5.2.3 => 5.2.3 
    @storybook/react: ^5.2.3 => 5.2.3 

Additional context
I believe it has to do with addDecorates(withKnobs),
reproducible example in my portfolio: https://github.com/denvash/dennisvash.com

1. yarn install
2. yarn storybook

[shilman]

Duplicate to #8080 fixed in 5.2.4