qml uses C++ sqlquerymodel, when there is no data in the database table, qml shows that the property is not defined

Question

    Text {
        id: test1
        anchors.top: test.bottom
        anchors.topMargin: 5
        text: lat
        font.pixelSize: 14
   }

qrc:/main.qml:70: ReferenceError: lat is not defined

when there is data in the database display is normal

Timer{
        interval: 3000;
        running: true;
        repeat: true;
        onTriggered: {
            sqlModel.insertHistory(22.58369099635166, 113.94935604230989)
        }
    }

SqlQueryModel {
        id: sqlModel
        query: "select * from history order by rowid desc"
    }