layui 错误 Cannot read property 'innerHTML'

HTML 代码：

class="layui-form-item">
    class="layui-form-label">联动选择框
    
class="layui-input-block">
        
class="layui-inline">
            name="now_province_id" lay-filter="now_province_id">
                value="">请选择省
                {volist name="area" id="val" key="k"}
                value="{$k}" {$model->now_province_id == $k ? 'selected':''}> {$val}
                {/volist}
            
        
        
class="layui-inline">
            name="now_city_id" lay-filter="now_city_id" id="now_city_id">
                {if $model->now_city_id}
                value="{$model->now_city_id}">now_city_id)?>
                {else /}
                {/if}
            
        
        
class="layui-inline">
            name="now_district_id" id="now_district_id">
                {if $model->now_city_id}
                value="{$model->now_district_id}">now_district_id)?>
                {else /}
                {/if}
            
        
    

通过js联动是出现错误

经过多次的百度之后还是没有找到问题所在，最后发现了这个问题的所在是第二个、第三个select 没有option

最后的代码为：

class="layui-form-item">
    class="layui-form-label">联动选择框
    
class="layui-input-block">
        
class="layui-inline">
            name="now_province_id" lay-filter="now_province_id">
                value="">请选择省
                {volist name="area" id="val" key="k"}
                value="{$k}" {$model->now_province_id == $k ? 'selected':''}> {$val}
                {/volist}
            
        
        
class="layui-inline">
            name="now_city_id" lay-filter="now_city_id" id="now_city_id">
                {if $model->now_city_id}
                value="{$model->now_city_id}">now_city_id)?>
                {else /}
                value="0">请选择
                {/if}
            
        
        
class="layui-inline">
            name="now_district_id" id="now_district_id">
                {if $model->now_city_id}
                value="{$model->now_district_id}">now_district_id)?>
                {else /}
                value="0">请选择
                {/if}