Fix serendipity_detectLang error when no lang is set

Happens in a test environment

Author: onli

include/compat.inc.php

@@ -396,6 +396,9 @@ function serendipity_getCharset() {
 function serendipity_detectLang($use_include = false) {
     global $serendipity;
 
+    if ($serendipity['languages'] == null) {
+        return null;
+    }
     $supported_languages = array_keys($serendipity['languages']);
     $possible_languages = explode(',', (isset($_SERVER['HTTP_ACCEPT_LANGUAGE']) ? $_SERVER['HTTP_ACCEPT_LANGUAGE'] : ''));
     if (is_array($possible_languages)) {

include/functions_smarty.inc.php

@@ -980,7 +980,6 @@ function serendipity_smarty_init($vars = array()) {
             // Beware: Smarty is used in the Admin backend, despite of this.
             include_once $template_dir . '/template.inc.php';
         } else {
-
             // Backend template overwritten here (NOT earlier due to frontend specific check)
             if (defined('IN_serendipity_admin')) {
                 $template_dir = $serendipity['serendipityPath'] . $serendipity['templatePath'] . $serendipity['template_backend'];