Internal Server Error

/www/wwwroot/shinatian/view/home/moon_shi.html:81
    79|           
月出时间：<%=think.datetime(moonrise,'YYYY-MM-DD HH:mm:ss')%>
    80|           
月落时间：<%=think.datetime(moonset,'YYYY-MM-DD HH:mm:ss')%>
 >> 81|           
月照时长：<%=controller.picTime((moonset.getTime()-moonrise.getTime())/1000)%>
    82|           

    83|             经度：东经
    84|             <%=jingwei.lon%>（<%=controller.toDegrees(jingwei.lon)%>）

Cannot read property 'getTime' of undefined