hotfix: On update of profile image, an error is returned from the mongoose function findByIdAndUpdate.

A detailed explanation can be found here: https://stackoverflow.com/questions/66370059/findoneandupdate-callback-must-be-a-function-got-object-object-nodejs-mon

Also a loop after updating profile image as !req.file checks if there is no file. But using result.url with return the accurate response by checking if image URL was updates on the db.