Fix path for errors raised for federated nodes

I opened a PR fixing the problem described in issue Top-level errors `path` field has incorrect value in case of nested service call · Issue #354 · apollographql/federation · GitHub

The changes seem major, so I wanted to ask is it possible to review it in the near future? The fixes are actively used in our projects and seem to be very useful, I’m afraid they may become outdated over time.
PR - Fix path for errors raised for federated nodes by lndbaryshnikov · Pull Request #988 · apollographql/federation · GitHub

Thank you.