bugfix: The defaultLanguageMap property of SimpleSAML\Locale\Language is static.

Therefore, it should be accessed using self, not $this.

lib/SimpleSAML/Locale/Language.php

@@ -333,8 +333,8 @@ class Language
      */
     public function getLanguageCodeAlias($langcode)
     {
-        if (isset($this->defaultLanguageMap[$langcode])) {
-            return $this->defaultLanguageMap[$langcode];
+        if (isset(self::$defaultLanguageMap[$langcode])) {
+            return self::$defaultLanguageMap[$langcode];
         }
         // No alias found, which is fine
         return null;