title: incorrect checksum for freed object
body: <p>On POSTing data to my expressjs app, this is what I am getting:</p>
  
  <pre><code>node(58287,0x7fff771ad960) malloc: *** error for object 0x7ff8a8600c58: incorrect
      checksum for freed object - object was probably modified after being freed.
  *** set a breakpoint in malloc_error_break to debug
  Abort trap: 6
  </code></pre>
  
  <p>Any idea why?</p>
  
  <p><strong>Update:</strong></p>
  
  <p>Here is some code:</p>
  
  <p><strong>Client side:</strong></p>
  
  <pre><code>$.ajax({
   url: 'user/' + id,
   type: 'POST',
   dataType:'JSON',
   data: JSON.stringify(data),
   success: function(response){
    console.log(response);
   }      
  });
  </code></pre>
  
  <p><strong>Server side:</strong></p>
  
  <pre><code>app.post('/user/:id', function(req,res){
    var id = req.params.id;
    console.log(data);
  });
  </code></pre>
  
  <p>When I <strong>use JSON.stringify</strong> on the client side, I am hitting this weird error:</p>
  
  <blockquote>
    <p>node(58461,0x7fff771ad960) malloc: <strong>* error for object
    0x7fa861d00e28: incorrect checksum for freed object - object was
    probably modified after being freed.
    *</strong> set a breakpoint in malloc_error_break to debug Abort trap: 6</p>
  </blockquote>
  
  <p>When I <strong>don't use JSON.stringify</strong> on the client side, I get <strong>'null' strings</strong> on the server side.</p>
  
  <p>Any ideas on what I am doing wrong?</p>