WeakMap error in IE11

[ViggoV]

Hi. I am getting the following error in IE11 when running my Webpack/Babel app:

IE's debugger points to line 37 of core-js/internals/collection.js. If I remove the core-js/stable import from my app, the next WeakMap occurence will throw the same error. It was my impression, however, that core-js was supposed polyfill WeakMap in IE

I am using:

• core-js 3.8.3
• webpack 5.9.0
• @babel/core 7.12.9 (with /node_modules/ excluded)

I import 'core-js/stable as the first thing in my entry point.

I have tried the suggestion from Issue 485 with no luck.

[zloirock]

I'm not sure that it's a core-js issue - WeakMap#set should throw an error on primitive as a key. Please, add a reproducible example.

[ViggoV]

I threw this repo together: https://github.com/ViggoV/weakmap-error-repro

The error thrown is different, but it does throw on a core-js file mentioning WeakMaps. In any case, it is the only import used.

Thanks for your time

[ViggoV]

I solved my issue by reverting to the deprecated @babel/polyfill. I have tried a bunch of different configurations for Babel and Core-JS, but I was unable to replicate the behavior. It's probably rather a babel or webpack issue.