积木报表导出的时候出现了Blank expression的异常

一、概要

1、来源

　　积木报表版本号：1.4.2

2、异常现象

　　导出Excel失败

3、异常栈：

com.googlecode.aviator.exception.CompileExpressionErrorException: Blank expression
at com.googlecode.aviator.AviatorEvaluatorInstance.compile(AviatorEvaluatorInstance.java:1419)
at com.googlecode.aviator.AviatorEvaluatorInstance.compile(AviatorEvaluatorInstance.java:1413)
at com.googlecode.aviator.AviatorEvaluatorInstance.compile(AviatorEvaluatorInstance.java:1400)
at com.googlecode.aviator.AviatorEvaluatorInstance.compile(AviatorEvaluatorInstance.java:1535)
at org.jeecg.modules.jmreport.desreport.express.b.a(ExpressUtil.java:262)
at org.jeecg.modules.jmreport.desreport.express.a.a(ExpressHandler.java:259)
at org.jeecg.modules.jmreport.desreport.express.a.a(ExpressHandler.java:172)
at org.jeecg.modules.jmreport.desreport.express.a.(ExpressHandler.java:78)
at org.jeecg.modules.jmreport.desreport.express.b.a(ExpressUtil.java:239)
at org.jeecg.modules.jmreport.desreport.service.a.e.show(JimuReportServiceImpl.java:3545)
at org.jeecg.modules.jmreport.desreport.service.a.e$$FastClassBySpringCGLIB$$4daca651.invoke()
at org.springframework.cglib.proxy.MethodProxy.invoke(MethodProxy.java:218)
at org.springframework.aop.framework.CglibAopProxy$DynamicAdvisedInterceptor.intercept(CglibAopProxy.java:684)
at org.jeecg.modules.jmreport.desreport.service.a.e$$EnhancerBySpringCGLIB$$959bd496.show()
at org.jeecg.modules.jmreport.desreport.service.a.k.a(JmReportExportExcelImpl.java:258)
at org.jeecg.modules.jmreport.desreport.service.a.k.a(JmReportExportExcelImpl.java:213)
at org.jeecg.modules.jmreport.desreport.service.a.k.exportExcel(JmReportExportExcelImpl.java:117)
at org.jeecg.modules.jmreport.desreport.a.a.b(DesignReportController.java:1069)