[Bug] Production build breaks on npm update

[bodograumann]

Describe the bug

After updating from 6.4.8 to 6.4.9, storybook production build breaks.
It seems to be unable to parse mdx files correctly.
I will have to look more deeply into this.

[bodograumann]

I also get the following error at the beginning of the log:

ERR! Addon value should end in /register OR it should be a valid preset https://storybook.js.org/docs/react/addons/writing-presets/
ERR! [object Object]

[bodograumann]

Relevant main.js. Removing the docs addon seems to fix the problem. I was not able to reproduce the issue in a clean project yet though.

module.exports = {
  stories: ["../../src/**/*.stories.@(js|jsx|ts|tsx|mdx)"],
  core: {
    builder: "webpack5",
  },
  addons: [
    {
      name: "@storybook/addon-docs",
      options: {
        babelOptions: {
          presets: [
            [
              "@vue/cli-plugin-babel/preset",
              {
                jsx: false,
              },
            ],
          ],
        },
      },
    },
  ],
};

[bodograumann]

Seems like the relevant change is that the @storybook/addon-docs dependency is not flattened in package-lock.json, but only installed as node_modules/@storybook/addon-essentials/node_modules/@storybook/addon-docs:

Previously in package-lock.json:

    "node_modules/@storybook/addon-docs": {

Now:

    "node_modules/@storybook/addon-essentials/node_modules/@storybook/addon-docs": {

Might this be related to npm 8.3.0?

[bodograumann]

Explicitely installing @storybook/addon-docs besides @storybook/addon-essentials works around the problem.

[bodograumann]

I guess in the default config this works fine, so this can probably not be fixed here :-|.