corejs-upgrade-webpack-plugin causing problems

Describe the bug If you import fetch-mock (which relies on core-js v2), its core-js imports fail. If I hack storybook to remove the corejs-upgrade-webpack-plugin, everything seems to work fine.

Sample errors:

ERROR in ./node_modules/fetch-mock/es5/client.js
Module not found: Error: Cannot find module 'core-js/modules/es6.regexp.replace'
 @ ./node_modules/fetch-mock/es5/client.js 115:0-45
 @ ./src/stories/index.js
 @ ./.storybook/config.js
 @ multi ./node_modules/@storybook/core/dist/server/common/polyfills.js ./node_modules/@storybook/core/dist/server/preview/globals.js ./.storybook/config.js ./node_modules/webpack-hot-middleware/client.js?reload=true

To Reproduce Steps to reproduce the behavior:

1. Clone https://github.com/jdelStrother/corejs-demo (a create-react-app with storybook, and an import for fetch-mock)
2. Run yarn storybook

Expected behavior Storybook successfully builds

System:

• OS: MacOS 10.14.5
• Device: Macbook Pro 2016
• Version: 5.1.9

Additional context Fun fact: Naming your project “core-js-demo” is also a great way to break your storybook build since it matches the /core-js/ regexp that the plugin uses…

[Hypnosphi]

Fun fact: this issue is the second link in Google for “corejs-upgrade-webpack-plugin”

[nemoDreamer]

Fun fact: Naming your project “core-js-demo” is also a great way to break your storybook build since it matches the /core-js/ regexp that the plugin uses…

OMG… This error was only happening on CI, and has been taking up most of my time these past 2 days…

My branch was called issue/SG-16714-fix-core-js-dist-conflicts, which on CI gets baked into the workspace path…:

ERR! EntryModuleNotFoundError: Entry module not found: Error: Cannot find module '/mnt/data/jenkins/workspace/ix-core-js-dist-conflicts/node_modules/@storybook/core/node_modules/html-webpack-plugin/lib/loader.js!/mnt/data/jenkins/workspace/ix-core-js-dist-conflicts/node_modules/@storybook/core/dist/server/templates/index.ejs'

🤦‍♂