Hide protocol download link when we cannot get protocol meta

This means the user is not logged in to GitLab, is logged in but has no access or something else is awry

In any case, the link would likely lead them to a 404 or an empty page

portal/static/js/components/pages/Fachschaftssitzung.mjs

@@ -60,7 +60,7 @@ export const Fachschaftssitzung = {
                         name: "Aktuelles Protokoll bearbeiten",
                     }),
                 ),
-                m(
+                latestProtocol.meta && m(
                     "p",
                     m(ButtonAndTextLink, {
                         href: latestProtocol.meta?.downloadLink,