The Right and Wrong way to use Errors in Promises

test_errors.js

// 
// Wrong ways to use Errors in Promises
// 

// Passes Error constructor to next step in Promise chain
Promise.resolve('foo').then(val => {
    return Error('Bad Thing 1');
}).then(val => {
    console.log('LOG 1', val);
}).catch(err => {
    console.error('ERR 1', err);
});

// Passes Error Instance to next step in Promise chain
Promise.resolve('foo').then(val => {
    return new Error('Bad Thing 2');
}).then(val => {
    console.log('LOG 2', val);
}).catch(err => {
    console.error('ERR 2', err);
});

// Swallows Error constructor
// Passes undefined to next step in Promise Chain
Promise.resolve('foo').then(val => {
    Promise.reject(Error('Bad Thing 3'));
}).then(val => {
    console.log('LOG 3', val);
}).catch(err => {
    console.error('ERR 3', err);
});

// Swallows Error Instance
// Passes undefined to next step in promise chain
Promise.resolve('foo').then(val => {
    Promise.reject(new Error('Bad Thing 4'));
}).then(val => {
    console.log('LOG 4', val);
}).catch(err => {
    console.error('ERR 4', err);
});

// Swallows Error Instance
// Passes undefined to next step in promise chain
Promise.resolve('foo').then(val => {
    Promise.reject('Bad Thing 5');
}).then(val => {
    console.log('LOG 5', val);
}).catch(err => {
    console.error('ERR 5', err);
});

// Catches rejected Promise, but no Error is passed, only a String
Promise.resolve('foo').then(val => {
    return Promise.reject('Bad Thing 6');
}).then(val => {
    console.log('LOG 6', val);
}).catch(err => {
    console.error('ERR 6', err);
});


// 
// The right way to use Errors in Promises
// 

// Throw an Error instance
Promise.resolve('foo').then(val => {
    throw new Error('Bad Thing 7');
}).then(val => {
    console.log('LOG 7', val);
}).catch(err => {
    console.error('ERR 7', err);
});

// Return a rejected Promise contining an Error
Promise.resolve('foo').then(val => {
    return Promise.reject(Error('Bad Thing 8'));
}).then(val => {
    console.log('LOG 8', val);
}).catch(err => {
    console.error('ERR 8', err);
});

// Return a rejected promise containing an Error
Promise.resolve('foo').then(val => {
    return Promise.reject(new Error('Bad Thing 9'));
}).then(val => {
    console.log('LOG 9', val);
}).catch(err => {
    console.error('ERR 9', err);
});