fix node 16 for v2

[mansona]

This PR backports the fix from #230 into v2 of workerpool.

I also backported the change to Github CI and added Node 12 14 and 16 to the test matrix in a separate commit so you can see Node 16 fail in one commit and then see it being fixed in the next 👍

[josdejong]

Thanks Chris, looks good 👍

[josdejong]

I've just published v2.3.4.

It wasn't very straightforward: the tests where passing but the build was broken, I had to switch to a very old version of node.js, and also changed the fix to ES5 code (see 6bc5913)

[josdejong]

hm, now v2.3.4 is marked as latest on npm. Will publish a bug fix release on v6 to make that latest again...

[josdejong]

ok fixed now by publishing v6.1.5 😅

[mansona]

woops! thanks for sorting all that!

Also sorry I didn't notice that there was a build, I should have checked that 🙈

[josdejong]

You're welcome. Only if you try to publish a 4 year old library version again you realize how fast the ecosystem is moving...

In the latest versions of workerpool, the build is actually executed when testing, and there are tests to validate whether the generated library bundles actually do work.