Don't vendor lunr.js script
Rather than vendoring the lunr.js script inside this repository, the extension should copy it from the require path (node_modules) to the generated site. This will make maintenance easier, keep it in sync with the search index, and allow patch releases to be fetched automatically (when the extension is installed).
I don't see any reason why we need a flag for this. If the extension is delivering the search index, it's reasonable that it deliver the engine along with it. We could check if there is a file in the way and not attempt to overwrite it. Anything more than that, let's allow users to request it.
Edited by Dan Allen