RH2019 Full-text Search generator fails on generating output

I have a project which uses Hungarian as the default language, also the pages are set to this language.

When generating output it fails: 

<p class="debug">responsive_skin finished.</p>
<p class="debug">copy_assets finished.</p>
<p class="info">Processing full-text search data...</p>
<p class="debug">Cannot set property 'label' of undefined</p>
<p class="error"></p>
<p class="error">Failed to generate HU Responsive help. </p>
<p class = "log" >= == == == == == == == == = </p>

For me it seems the problem is with lunr, not registering the correct language tools (stemmer, trimmer, StopWordFilters).

If I'm using the same project with english settings it simply generates the output without much ado.