Node JS error crash after handling custom error - node.js

Question

the problem is the following. I'm using node js with express and mongo db for my backend. I'm new with node js so I will try to explain the problem.
I'm creating a endpoint to validate a confirmation code for emails validation and it's working fine when I found the problem doing a return and showing a code 200, but I want to display another error when is not found. So after try to validate a invalid code the backend crash and show the following error.
CONTROLLER
function confirmation(req, res, next) {
userService.confirmate(req.body)
.then (res.status(200).json({status:"ok"}))
.catch(err => next(err));
}
SERVICE
async function confirmate(body) {
User.findOneAndUpdate({token: body.code}, {$set: {isVerified: true}}, {upsert: false}, function(err,doc) {
if (err) {
// SOME ERROR
console.log(' error');
throw err; }
if (!doc) {
// NOT FOUND HANDLER
console.log('not found);
throw new Error('example')
}
// FOUNDED!
console.log("Updated");
return;
});
}
ERROR HANDLER
module.exports = errorHandler;
function errorHandler(err, req, res, next) {
if (typeof (err) === 'string') {
// custom application error
return res.status(400).json({ message: err });
}
if (err.name === 'ValidationError') {
// mongoose validation error
return res.status(400).json({ message: err.message });
}
if (err.name === 'UnauthorizedError') {
// jwt authentication error
return res.status(401).json({ message: 'Invalid Token' });
}
// default to 500 server error
return res.status(500).json({ message: err.message });
}
ERROR
D:\DESARROLLO\menuon-project\be-server\node_modules\mongodb\lib\utils.js:132
throw err;
^
Error: example
at D:\DESARROLLO\menuon-project\be-server\users\user.service.js:88:23
at D:\DESARROLLO\menuon-project\be-server\node_modules\mongoose\lib\model.js:4690:16
at model.Query.Query._completeOne (D:\DESARROLLO\menuon-project\be-server\node_modules\mongoose\lib\query.js:1932:12)
at cb (D:\DESARROLLO\menuon-project\be-server\node_modules\mongoose\lib\query.js:3285:11)
at D:\DESARROLLO\menuon-project\be-server\node_modules\mongoose\lib\query.js:3376:14
at D:\DESARROLLO\menuon-project\be-server\node_modules\mongoose\lib\query.js:4093:12
at result (D:\DESARROLLO\menuon-project\be-server\node_modules\mongodb\lib\utils.js:414:17)
at session.endSession (D:\DESARROLLO\menuon-project\be-server\node_modules\mongodb\lib\utils.js:401:11)
at ClientSession.endSession (D:\DESARROLLO\menuon-project\be-server\node_modules\mongodb-core\lib\sessions.js:129:41)
at executeCallback (D:\DESARROLLO\menuon-project\be-server\node_modules\mongodb\lib\utils.js:397:17)
at handleCallback (D:\DESARROLLO\menuon-project\be-server\node_modules\mongodb\lib\utils.js:128:55)
at executeCommand (D:\DESARROLLO\menuon-project\be-server\node_modules\mongodb\lib\operations\collection_ops.js:558:12)
at handleCallback (D:\DESARROLLO\menuon-project\be-server\node_modules\mongodb\lib\utils.js:128:55)
at db.s.topology.command (D:\DESARROLLO\menuon-project\be-server\node_modules\mongodb\lib\operations\db_ops.js:516:5)
at D:\DESARROLLO\menuon-project\be-server\node_modules\mongodb-core\lib\connection\pool.js:532:18
at process._tickCallback (internal/process/next_tick.js:61:11)
Emitted 'error' event at:
at D:\DESARROLLO\menuon-project\be-server\node_modules\mongoose\lib\model.js:4692:13
at model.Query.Query._completeOne (D:\DESARROLLO\menuon-project\be-server\node_modules\mongoose\lib\query.js:1932:12)
[... lines matching original stack trace ...]
at process._tickCallback (internal/process/next_tick.js:61:11)
npm ERR! code ELIFECYCLE
npm ERR! errno 1
npm ERR! node-mongo-registration-login-api#1.0.0 start: `node ./server.js`
npm ERR! Exit status 1
npm ERR!
npm ERR! Failed at the node-mongo-registration-login-api#1.0.0 start script.
npm ERR! This is probably not a problem with npm. There is likely additional logging output above.
npm ERR! A complete log of this run can be found in:
npm ERR! C:\Users\Franco\AppData\Roaming\npm-cache\_logs\2019-08-10T16_55_39_844Z-debug.log