fix main.js (if date is undefined)

Author: soimort

__/js/main.js

@@ -1,13 +1,14 @@
 /* Akai (pandoc HTML5 template)
  * designer:     soimort
- * last updated: 2017-03-24
+ * last updated: 2018-04-13
  */
 
 document.addEventListener('DOMContentLoaded', function() {
 
   // convert dates to human-readable format
   var options = { year: 'numeric', month: 'long', day: 'numeric' },
       date = document.getElementsByTagName('h3')[0];
-  date.innerText = new Date(date.innerText).toLocaleDateString('en-GB', options);
+  if (date)
+    date.innerText = new Date(date.innerText).toLocaleDateString('en-GB', options);
 
 });