log a user in an Express controller (mongoose)

login.js

const jwt = require('jsonwebtoken');
// you'll also need some mongoose User model

exports.login = async (req, res, next) => {
    let usr;
    try {
        usr = await User.findOne({ email: req.body.email });
    } catch (error) {
        res.status(500).json({
            data: null,
            msg: 'sorry we experienced an issue, please try again later',
            success: false
        });
        return;
    }
    if (!usr) {
        res.status(401).json({
            data: null,
            msg: 'no user found',
            success: false
        });
        return;
    } 
    let isPwdValid;
    try {
        isPwdValid = await bcrypt.compare(req.body.password, usr.password);
    } catch (error) {
        res.status(500).json({
            data: null,
            msg: 'sorry we experienced an issue, please try again later',
            success: false
        });
        return;        
    }
    if (!isPwdValid) {
        res.status(401).json({
            data: null,
            msg: 'invalid credentials',
            success: false
        });
        return;
    }
    res.status(200).json({
        data: {
            isAdmin: usr.isAdmin,
            token: jwt.sign(
                { userId: usr._id },
                process.env.RANDOM_SECRET_TOKEN,
                { expiresIn: '24h' }
            ),
            userId: usr._id
        },
        msg: 'login successful',
        success: true
    });
};