How are these kinds of published errors managed?

I suggest that you write to the Journal to point out this error. It is, after all, still an error and needs to be corrected.

If someone were to write to us describing such an error, one of our editors would confirm the validity of the claim. If upheld, then this will result in a small correction (perhaps one to two lines) to be printed in the next issue of the journal. This is the practice at least in the journals in health and medicine that I help edit.

In the electronic versions of the manuscript, we would make the change in-house and release a new version of the paper with a notation at the end of the article specifying the change. That way, no new versions would be released with the error still in place.

We would issue an apology, too, and a statement that the inferences and conclusions were not affected.

This error would not be significant enough to alert indexing services. Also, this would not trigger a need for us to investigate the source of the error or to review our processes.

It's a very small error and clearly just a typo, so don't worry too much. Probably best to notify the Journal as they might have an opportunity to change it, but if they don't I think anyone reading it would thing "wait that doesn't make sense or fit with the rest of the paper. Oh, they must have missed out the word 'not'." and then carry on reading.