webpack complaining about babelrc missing present-env config for corejs

[khatibda]

Type of issue

it's a webpack warning, not a bug per se, but should be heeded and fixed.

Description

we recently updated babelrc to include "useBuiltIns" in babel/preset-env. #7641
as a result, when we do a webpack build in our own pipeline, we get the following new webpack warning:

web-frontend-1 | WARNING (@babel/preset-env): We noticed you're using the useBuiltInsoption without declaring a core-js version. Currently, we assume version 2.x when no version is passed. Since this default version will likely change in future versions of Babel, we recommend explicitly setting the core-js version you are using via thecorejsoption. web-frontend-1 | web-frontend-1 | You should also be sure that the version you pass to thecorejsoption matches the version specified in yourpackage.json's dependenciessection. If it doesn't, you need to run one of the following commands: web-frontend-1 | web-frontend-1 | npm install --save core-js@2 npm install --save core-js@3 web-frontend-1 | yarn add core-js@2 yarn add core-js@3 web-frontend-1 | More info about useBuiltIns: https://babeljs.io/docs/en/babel-preset-env#usebuiltins web-frontend-1 | More info about core-js: https://babeljs.io/docs/en/babel-preset-env#corejs

As per babel details, we need to specify the core-js version used.
https://babeljs.io/docs/en/babel-preset-env#corejs

something like this:
"useBuiltIns": "entry", // or "usage"
"corejs": { "version": "3.13.0"}, // or whatever version used in package.json, e.g. currently "3.13.0"

Steps to reproduce

run a webpack build, assuming you're building prebid.js in your own pipeline

Other information

looks like this fix was included in v6.1

[khatibda]

tagging @ChrisHuie and @patmmccann for visibility re #7641

[ChrisHuie]

#7942 - I think should solve this when it is merged.

[ChrisHuie]

@khatibda planning to address this shortly. Likely with the next release