fix import helpers

[LeeLenaleee]

Resolves: #10547

[etimberg]

What's a good way to test this?

[ghost]

It looks ok

[LeeLenaleee]

What's a good way to test this?

Steps I use to test these kind of things:

1. Create clean project: npx create-react-app test-chartjs-changes
2. Install chart.js: npm i chart.js
3. Go into the node modules folder into chart.js and make the changes you want to test
4. Remove the .bin and .cache folder in the root of the node modules
5. Run npm i again so it builds all the packages again but with your own changes
6. Import a helper function in App.js: import {merge} from 'chart.js/helpers'
7. Put console log to see it got imported correctly: console.log(merge)
8. Run npm start to run dev server
9. It should build without errors and show the merge function in the console

[kurkle]

We could add simple projects as integration tests for different platforms.

[LeeLenaleee]

@etimberg can you do a manual release of 3.9.1 because this also affects plugins.

[etimberg]

Will do! I think it can be done entirely with the GitHub UI but will need to manually create the release on the correct branch.

@LeeLenaleee can you send a PR to the 3.9 branch bumping the package.json version number?