array_filter 'NULL' check

Thanks for reporting this issue and providing a patch!
I’d actually say that if the value is already NULL or otherwise empty we can just return early, so modified the patch accordingly. But yes, it does look like an obvious bug there (though it seems it’s not that simple to trigger).

Attached is my proposed solution, please test/review and I can commit.
In any case, thanks again!

Do you maybe still have a few more detail regarding when this happens? Which filter plugin is it exactly, and with what setup? There might be another bug causing this, actually, as I think $this->value should be an array at this point (though potentially empty).

Well, should still be an improvement.
Committed. Thanks again!

Automatically closed - issue fixed for 2 weeks with no activity.