Restore missing error handling for user login

[Gabriel Lebec]

boilermaker/server/auth/index.js

Lines 5 to 16 in 3f14ba6

 router.post('/login', async (req, res, next) => { 
   const user = await User.findOne({where: {email: req.body.email}}) 
   if (!user) { 
     console.log('No such user found:', req.body.email) 
     res.status(401).send('Wrong username and/or password') 
   } else if (!user.correctPassword(req.body.password)) { 
     console.log('Incorrect password for user:', req.body.email) 
     res.status(401).send('Wrong username and/or password') 
   } else { 
     req.login(user, err => (err ? next(err) : res.json(user))) 
   } 
 }) 

During #20 we accidentally forgot to include error handling for failed login attempts. We should put that back.