Fixed null reference on resize.

src/html/js/entries.js

@@ -507,7 +507,7 @@ $(window).resize(function() {
     window.chart.replot({resetAxes: true});
   }
 
-  if(window.chart) {
+  if(window.pieChart) {
     window.pieChart.replot({resetAxes: true});
   }
 });