Check room length when getting name from url

roomunlock.html

@@ -82,7 +82,7 @@
     const roomUrl = document.getElementById('roomUrl');
 
     let room = window.location.href.substring(window.location.href.lastIndexOf('/') + 1)
-    if (room !== "raumfreischaltung") {
+    if (room.length > 2 && room !== "raumfreischaltung") {
         roomField.value = room;
         get_room();
     }