How to get Algolia docsearch indexBase work for GitHub pages?

[f-w]

I have a doc site called NotifyBC built with VuePress v1 and deployed to GH pages that shows multiple versions of the software. Each version is a VuePress site by itself with its own base. For example, version 4.1 has base /NotifyBC/version/4.1/ as opposed to the root base /NotifyBC/. I have to get Algolia search work regardless with version user is at.

In VuePress v1 I was able to overwrite handleSelected function to achieve this. In VuePress v2 however, it's not trivial to overwrite the default implementation. Furthermore, even though VuePress v2 indexBase docsearch option works in dev mode, it doesn't work in GH pages. I therefore believe indexBase is implemented at server-side and requires nodejs support.

You can see the problem by searching in preview site, which is akin to version site except written in VuePress v2 and unpublished. You'll find base of search results, when navigated, is kind of duplicated and got 404.