Request to non-existing tiles

I have created custom tiles using TileMill. extracted tiles as png images and adding them on base layer. using following code

var venu_map = new L.tileLayer('static/b18/{z}/{x}/{y}.png', {
               maxZoom:22,
              attribution: '&copy; <a href="http://ift.tt/VGR6Z6">OpenStreetMap</a> contributors'
              }).addTo(map);

It works fine. But for every zoomlevel change leaflet makes a number of(around 20 -30) requests to non existing tiles resulting in "NetworkError: 404 NOT FOUND. Complete error msg is "NetworkError: 404 NOT FOUND - http://ift.tt/1vRqf8e". The perticular image does not exist. Even after setting maxbounds this error show up. Any solutions?