javascript - Node.js: How to return a rejcted promise without getting UnhandledPromiseRejectionWarning -

i have function in module uses request-promise-native module query couchdb database:

userbyemail: (email) => {   const options = {     url: `${config.couchdb.url}/medlog/_design/user/_view/by_email_or_userid?key="${email}"`,     json: true,   };    return rp.get(options)     .then(users => users.rows.map(row => row.value))     .catch(reason => promise.reject(new error('test'))); } 

a second module contains function uses first one:

router.get('/checkemailexistence', (req, res) => {   couchdb.userbyemail(req.param('email'))     .then((userarray) => {       res.status(200).end(userarray.length > 0); // returns 'true' if @ least 1 user found     })     .catch((e) => {       winston.log('error', e.message);       res.status(500).end(e.message); }); 

in case there no database connection, promise request-promise-native module rejected. want catch rejection in second function , return internal server error caller. forward rejection request-promise-native module catch in first function , return new rejected promise.

unfortunately warning have unhandled promise rejection. how can solve issue?

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edit

i've seen used wrong codepath testing. coding above works without producing warning. sorry confusion.

this happen because promise always has return something.

you can fix 'issue' return null

router.get('/checkemailexistence', (req, res) => {   couchdb.userbyemail(req.param('email'))   .then((userarray) => {     res.status(200).end(userarray.length > 0); // returns 'true' if @ least 1 user found     return null   })   .catch((e) => {     winston.log('error', e.message);     res.status(500).end(e.message);     return null   }); });