fix for javascript/turbolink nav.render firing when element not found (#163)

Author: ddnexus

lib/javascripts/pagy.js

@@ -22,6 +22,7 @@ Pagy.nav = function(id, tags, sequels, param){
              widths.sort(function(a, b){return b-a});
 
              var render    = function(){
+                               if (document.getElementById(id) === null){ return }
                                if (container.clientWidth === 0) { rendering() }
                                var width, i, len;
                                for (i = 0, len = widths.length; i < len; i++) {