return i18n fields as string, fixes #1069

Closes #1069

Merge request studip/studip!634

lib/classes/globalsearch/GlobalSearchCourses.php

@@ -204,7 +204,7 @@ class GlobalSearchCourses extends GlobalSearchModule implements GlobalSearchFull
             'number'        => self::mark($course->veranstaltungsnummer, $search),
             'name'          => self::mark($course->getFullname(), $search),
             'url'           => URLHelper::getURL("dispatch.php/course/details/index/{$course->id}", [], true),
-            'date'          => $semester->token ?: $semester->name,
+            'date'          => (string) $semester->token ?: (string) $semester->name,
             'dates'         => $turnus_string,
             'has_children'  => count($course->children) > 0,
             'children'      => $result_children,

lib/classes/globalsearch/GlobalSearchMyCourses.php

@@ -146,7 +146,7 @@ class GlobalSearchMyCourses extends GlobalSearchModule
             'number'        => self::mark($course->veranstaltungsnummer, $search),
             'name'          => self::mark($course->getFullname(), $search),
             'url'           => URLHelper::getURL('seminar_main.php', ['cid' => $course->id], true),
-            'date'          => $semester->token ?: $semester->name,
+            'date'          => (string) $semester->token ?: (string) $semester->name,
             'dates'         => $turnus_string,
             'has_children'  => count($course->children) > 0,
             'children'      => $result_children,