Check for invitations which were used already

routes/profile.js

@@ -84,6 +84,8 @@ DB.getDB.then((DB)=>{
         if(!email) return res.json({status: "provide valid email"});
         let r = await DB.getInvitation(email);
         if(!r) return res.json({status: "no invitation found with that email"});
+        let isUserAlreadyRegistered = await DB.getUser(email);
+        if(isUserAlreadyRegistered && isUserAlreadyRegistered._id) return res.json({status: "This user is already registered"});
         return res.json({status: "ok", ... r});
     });