Null check for frameElement to avoid firebug error when loading default home page after login in

jeecg-framework/src/main/webapp/plug-in/tools/curdtools.js

@@ -8,7 +8,7 @@ window.onerror = function() {
 var iframe;// iframe操作对象
 var win;//窗口对象
 var gridname="";//操作datagrid对象名称
-if ( "" != frameElement.api) {
+if ( frameElement) {
     var windowapi = frameElement.api, W = windowapi.opener;//内容页中调用窗口实例对象接口
 }
 function upload(curform) {