avoid route to be executed when "clientError" is emitted

How to avoid handler to be called when "clientError" is emitted? It can be done?

var server=http.createServer(app).listen(app.get('port'), function(){
  console.log("Express HTTP server listening on port " + app.get('port'));
}).on('clientError', function(ex,socket){
    console.log(ex); 
    //socket is undefined here
});


app.post('/delete-files',handler);

handler = function(req,res){
  console.log(req.body.files)
  // other stuff goes here
}

I am trying to crash my app by intercepting and modifying POST params with Tamper Data. Post is sent by jQuery post function. Post param is an array. When I modify the array with Tamper Data I got:

Error: Parse Error 
undefined
Error: Parse Error
undefined   
Error: Parse Error
undefined 
Error: Parse Error
undefined
Error: Parse Error 
undefined
Error: Parse Error
undefined
Error: Parse Error
undefined

1. Parse Error is from "clientError" event callback
2. undefined from console.log(req.body.files)

It is always called exactly 7 times.

This should be something related to AJAX

POST param array:

files[] file1.txt

POST param after Tamper Data modification

files[] file5.txt