Little snippet to show that you must catch anidated promises or return them to be catched by outer `catch()`

anidated.promises.dont.bubble.up.errors.js

'use strict';


const willResolve = (value = true) => Promise.resolve(value);

const willReject = (msg = 'This is fucked up!') => Promise.reject(new Error(msg));

const toBeOrNotToBe = (value = true, msg = 'This may resolve... Or not') => {
  (Math.random() > 0.5) ? Promise.resolve(value) : Promise.reject(msg);
};

// Anidated promise doesn't get catched by outer `catch()`. The next message will appear at the end:
// UnhandledPromiseRejectionWarning: Unhandled promise rejection (rejection id: 4): Error: This is fucked up!
willResolve().then(() => {
  willReject().then(() => console.log('reached reject'));
})
  .catch((error) => console.log('Outter catcher:', error));


// An inner `catch()` is needed
willResolve().then(() => {
  willReject(`Let's catch this one.`).then(() => console.log('reached reject'))
  .catch((error) => console.log('Anidated catch:', error));
})
  .catch((error) => console.log(error));

// Or better...
willResolve().then(() => {
  return willReject('Catch this one too.').then(() => console.log(`This code won't run.`));
})
  .catch((error) => console.log(`Now we're catching everything:`, error));


// in case you wanna play in the node console
module.exports = {
  willResolve,
  willReject,
  toBeOrNotToBe,
};