el-date-picker在清空时，控制台报错

问题：el-date-picker 在清空时，控制台报错

vue.js:634 [Vue warn]: Error in v-on handler: "TypeError: Cannot read property '0' of null"

found in

---> <ElDatePicker> at packages/date-picker/src/picker.vue
       <Root>

解决方法

<el-date-picker
    v-model="value1"
    type="datetimerange"
    format="yyyy-MM-dd HH:mm"
    value-format="yyyy-MM-dd HH:mm:ss"
    range-separator="至"
    start-placeholder="开始日期"
    end-placeholder="结束日期"
    @change="getTime"
    >
</el-date-picker>

getTime(){
    if (!this.value1) {//解决value1为null时，控制台报错的问题
        this.value1 = []
    }
    ... ...
    ... ...
    ... ...
}