small bug fix, to prevent some errors popping up

Author: rossengeorgiev

cache.manifest

@@ -1,5 +1,5 @@
 CACHE MANIFEST
-# version 82
+# version 83
 
 # gogole maps files
 http://maps.google.com/maps/api/js?v=3.10&sensor=false&key=AIzaSyCOqkcNey4CCyG4X0X5qxHAhCgD8g5DwXg

js/plot_config.js

@@ -92,7 +92,7 @@ function updateLegend() {
             }
             y = y.toFixed(2);
 
-            if(p1[1] == null || p2[1] == null) y = null;
+            if((p1 && p1[1] == null) || (p2 && p2[1] == null)) y = null;
         }
         legend.eq(i).text(series.label.replace(/=.*/, "= " + y));
     }