Avoid return and callArg* clearing each other's state

[fatso83]

Purpose (TL;DR) - mandatory

This partially reverts changes done in #2567, as the clearing of state was a bit too invasive. It is fully possible to have functions that both call callbacks and return values, which was made impossible by this change.

I kept the tests, which proves this fix is not affecting the intent of the original fix, and additionally added a regression test for #2572 to make sure it keeps that way.

How to verify - mandatory

1. Check out this branch
2. npm install

Checklist for author

• [x] npm run lint passes
• [x] References to standard library functions are cached.