fix: correct meta tag for idphint

templates/selectsource.twig

@@ -19,7 +19,8 @@
     <script src="/{{baseurlpath}}module.php/campusmultiauth/resources/jquery-3.6.0.min.js"></script>
     <script src="/{{baseurlpath}}module.php/campusmultiauth/resources/selectize/js/standalone/selectize.min.js"></script>
 
-    <meta name="idphint" value="{% if idphint is defined %}{{ idphint | json_encode }}{% endif %}">
+    {% if idphint is not defined %}{% set idphint = [] %}{% endif %}
+    <meta name="idphint" content="{{ idphint | json_encode }}">
 
     <script src="/{{baseurlpath}}module.php/campusmultiauth/resources/campus-idp.js"></script>
 {% endblock %}