tags, and assignedby nul

graph/resolvers/tag_link.js

@@ -1,6 +1,6 @@
 const TagLink = {
   assigned_by({assigned_by}, _, {user, loaders: {Users}}) {
-    if (user && user.hasRoles('ADMIN')) {
+    if (user && user.hasRoles('ADMIN') && assigned_by != null) {
       return Users.getByID.load(assigned_by);
     }
   }