return error when register user with used email:

index.js

@@ -76,21 +76,21 @@ DB.getDB.then((DB)=>{
         if(!username || !password || !email) return res.json({status: "fail"})
         //const hashedPassword = await bcrypt.hash(password, 10);
         const hashedPassword = await bcrypt.hash(password, 10);
-        const success = await DB.newUser({
-            username: username,
-            email: email,
+        const response = await DB.newUser({
+            username: username.toLowerCase(),
+            email: email.toLowerCase(),
             password: hashedPassword
         });
-        if(success){
+        if(!response.toLowerCase){
             let user = {
-                userid: success.insertedId,
+                userid: response.insertedId,
                 profile: profile,
             }
             const userObj = new Profile(user);
             await DB.newProfile(userObj);
             return await login(req, res);
         }
-        res.redirect('/signup');
+        return res.json({status: response})
     }
     app.route('/signup').get(async (req, res) => {
         return await signup(req, res);
@@ -125,7 +125,6 @@ DB.getDB.then((DB)=>{
         res.cookie('session_id', doc.insertedId, cookiesOptions);
         //Chooses the most recent update profile
         const latestProfile = await DB.latestProfile(user._id);
-        console.log("latestProfile", latestProfile)
         res.cookie('profile_id', latestProfile._id, cookiesOptions);
         return res.json({
             status: "ok",

mongoDB.js

@@ -50,8 +50,12 @@ const getDB = new Promise((resolve, reject) => {
 
         DB.newUser = (userInformation)=>{
             return DB.usersCol.insertOne(userInformation).catch((err)=>{
+                if (err.name === 'MongoError' && err.code === 11000) {
+                    // Duplicate username
+                    return "User already exists";
+                }
                 console.log(err);
-                return false;
+                return "System Error";
             });
         };