thinkphp5报错：Indirect modification of overloaded element

在使用Thinkphp5.1进行项目开发的时候，报出了一个错误：Indirect modification of overloaded element....has no effect。

详细代码如下：

/**
* @title 需求大厅
* @author zxn
* @url /member/master/need_hall
* @param name:fix_type type:integer require:0 default: desc:安装类型
* @param name:status type:integer require:0 default: desc:派工状态
* @method POST
* @header name:Authorization require:1 default:1455523e6d407a3c desc:token
*/
public function need_hall(){
$param = $this->request->param();
$map = [];
$map[] = ['is_deleted','=',0];
if(isset($param['fix_type']) && $param['fix_type'] >= 0) $map[] = ['fix_type','=',intval($param['fix_type'])];
if(isset($param['status']) && in_array($param['status'],[0,1])) $map[] = ['status','=',intval($param['status'])];
$list = MemberDemandModel::where($map)->with('member')
->order('id desc')
->field('master_id,master_name,master_mobile,master_time,is_deleted,mobile,address',true)
->paginate()
->each(function ($item){
$images = explode(",",$item['images']);
$image_list = [];
foreach ($images as &$key){
$image_list[] = set_up_img($key);
}
$item['images'] = $image_list;
$item['fix_type'] = MasterModel::getFixTypeAttr($item['fix_type']);
$item['member']['avatar'] = getAvatar($item['member']['avatar']);
return $item;
});
return returnData(1,'请求成功',$list);
}