Answers for "(node:65723) UnhandledPromiseRejectionWarning: Error [ERR_HTTP_HEADERS_SENT]: Cannot set headers after they are sent to the client"

(node:65723) UnhandledPromiseRejectionWarning: Error [ERR_HTTP_HEADERS_SENT]: Cannot set headers after they are sent to the client

router.get("/userprofile", passport.authenticate('jwt', { session: false }), (req, res) => {

  Profile.findOne({ user: req.user.id }).then(profile => {
    if (!profile) {
      return res.status(404).json({ error: "No Profile Found" });
    }
    else {
      res.json(profile);
    }
  }).catch(err => {
    console.log(err);
  })
});