Only load Lunr languages that exist in theme

ref #1445 (comment)

Author: mmistakes

_includes/scripts.html

@@ -11,8 +11,14 @@
   <script src="{{ '/assets/js/main.min.js' | absolute_url }}"></script>
 {% endif %}
 
-{% if site.search == true or page.layout == 'search' %}
+{% if site.search == true or page.layout == "search" %}
   {% assign lang = site.locale | slice: 0,2 | default: "en" %}
+  {% case lang %}
+  {% when "gr" %}
+    {% assign lang = "gr" %}
+  {% else %}
+    {% assign lang = "en" %}
+  {% endcase %}
   <script src="{{ '/assets/js/lunr.min.js' | absolute_url }}"></script>
   <script src="{{ '/assets/js/lunr-' | append: lang | append: '.js' | absolute_url }}"></script>
 {% endif %}