Fixes #279.

resources/vue/courseware-index-app.js

@@ -71,14 +71,9 @@ const mountApp = (STUDIP, createApp, element) => {
         },
     ];
 
-    let pathname = new URL(STUDIP.ABSOLUTE_URI_STUDIP).pathname;
-    if (pathname.endsWith('/')) {
-        pathname = pathname + '/';
-    }
     const base = STUDIP.URLHelper.parameters.cid
-          ? `${pathname}dispatch.php/course/courseware/?cid=${STUDIP.URLHelper.parameters.cid}`
-          : `${pathname}dispatch.php/contents/courseware/courseware`;
-
+        ? STUDIP.URLHelper.getURL('dispatch.php/course/courseware', { cid: STUDIP.URLHelper.parameters.cid }, true)
+        : STUDIP.URLHelper.getURL('dispatch.php/contents/courseware/courseware');
     const router = new VueRouter({
         base,
         routes,