Review that targets code that makes the question off-topic, then question is updated

Question

I was looking around for zombies and fell on this question : Importing text into PANDAS and counting certain words

The review is basically pointing runtime errors in the code that would've made the question off-topic. When the OP saw this review, he/she edited the question to heed the advice in the comments from the answerer, which shouldn't have been done. Now, the answer is worthless because the question was edited, but the question should've been off-topic in the first place.

So I'm wondering what to do with the answer, that's worthless now. I'm also wondering what to do with the question, considering the facts above.

Should nothing be done? Act like the answer isn't there and the question was fine in the first place?

Answer 1

Traditionally, answers to off-topic questions (especially to those questions that are obviously off-topic) are not considered valid answers for the purposes of answer invalidation rollbacks.

We'd rather have an on-topic question and inconvenience an answerer than having to roll back the question into an off-topic state just to avoid invalidating an answer.

In this case the matter is slightly complicated by the fact that the question was asked and answered over a year ago. The relevant policy has been around since two years before that, though.

As such the answerer should be notified their answer was to an off-topic state of the question. In addition the question should remain as is (you might as well answer it, ~wink wink, nudge nudge). In this specific case the answer might need to be deleted if its owner does not edit it.