language navigation menu caused error when there is only one language

app/views/header2.htm

@@ -1,6 +1,6 @@
 <header>
 
-  <check if="{{ @navi.languages }}">
+  <check if="{{ isset(@navi.languages) }}">
     <div class="languages">
       <include href="navigation.htm" with="menu={{ @navi.languages }}" />
     </div>