title: Can not read property "Buffer" of "undefined"
body: <p>I am building an app in which I am filling a form which also has files. I am getting files from "req.file" and other things from "req.body". the "file" is not "required". The user can attach or cannot attach. when the user attaches, all goes well but when a user does not attach the file I found this error. <code>can not read property "buffer" of undefined.</code>. I have set mongoose schema type of "image" is "Buffer". Here is my code when I get a file and other data from "req".</p>
  
  <pre><code>image: req.file.buffer,
  
  geolocation: req.body.geolocation,
  
  details: req.body.details,
  
  location: req.body.location,
  
  status: req.body.status,
  
  spam: req.body.spam,
  </code></pre>