removed uniqueness of email, check unique of username on POST for user

migrations/20200213223053-create-user.js

@@ -15,8 +15,7 @@ module.exports = {
       },
       email: {
         type: Sequelize.STRING,
-        allowNull: false,
-        unique: true
+        allowNull: false
       },
       avatar: {
         type: Sequelize.STRING

routes/users.js

@@ -62,14 +62,14 @@ router.post('/', async (req, res, next) => {
 
   const existing = await User.findOne({
     where: {
-      email: req.body.email
+      username: req.body.username
     }
   })
 
   if (existing) {
     return res.status(400).json({
       status: 'error',
-      result: 'email_exists'
+      result: 'username_exists'
     })
   }