Marc had noted that sometime wiki's incremental search result shows as a tiny white empty box. No amount of reloading clears this condition.
There are a few commits that help resolve Marc's search problem.
Starting with capture search failures which puts the search in a try... catch and returns an empty array if the search fails. This captures the case of the search index getting corrupt, and the search failing. Which is what was happening with Marc. github 
Next the was updating minisearch, amongst other changes this changes the index serialization format. This should be easier to read and diagnose what is happening if we get a repeat of the index getting corrupt. github
And finally text extract was also put into a try... catch to catch trying to extract text from any items where text is expected but missing. This is likely to be root cause of the problem Marc had, as there was a page with a markdown item without text. github