error-pattern.js

let saveUser = async function(){
    let err, user;
    
    [err, user] = await to(UserModel.findById(1));
    
    if(err) throwError(err.message, true);
    
    user.name = “this rocks”
    
    [err, user] = await to(user.save());
    
    if(err) throwError(‘error on saving user’);
    
    return user;
}
//*** HELPER FUNCTIONS *** 
//*** npm install parse-error
pe = require('parse-error');
to = function(promise) {
    return promise
    .then(data => {
        return [null, data];
    }).catch(err =>
        [pe(err)]
    );
}
throwError = function(err_message, log){ // throwError stands for Throw Error
    if(log === true){
        console.error(err_message);
    }
    throw new Error(err_message);
}