this has been rewritten to undefined

[soelen]

I recently integrated redux-toolkit in one of my projects and my rollup based building setup throws a warning out:

(!) `this` has been rewritten to `undefined`
https://rollupjs.org/guide/en/#error-this-is-undefined
node_modules\@reduxjs\toolkit\dist\redux-toolkit.esm.js
1: var __extends = (this && this.__extends) || (function () {
                    ^
2:     var extendStatics = function (d, b) {
3:         extendStatics = Object.setPrototypeOf ||
...and 5 other occurrences

Perhaps this is nothing to be concerned about but I decided to create an Issue just in case.

I also integrated redux-toolkit in one of my public projects in order to make this issue reproduceable:

How to reproduce

• clone Workbox Tests
• run npm i
• run npm run build

Files of interest

My whole redux setup is inside the store folder. I use Webcomponents/Lit to establish a component architecture. My base class page-element is subscribed to the store and some of my pages make use of it.

[phryneas]

That's nothing to worry about, that's just one bundler complaining about code from another bundler that is a bit defensive ;)

Nothing of that has been written by hand by us and it will be working 100%

[soelen]

Thanks a bunch @phryneas! For future googlers: I just put this in the rollup option onwarn prop; based on this solution:

// ...
export default {
  // ...
  onwarn(warning, warn) {
      if (warning.code === 'THIS_IS_UNDEFINED') return;
      warn(warning);
  },
  plugins: [
  // ...