动态bug修复

app/Admin/Controllers/DynamicController.php

@@ -37,7 +37,7 @@ class DynamicController extends AdminController
             if(isset($v)&&!empty($v)){
                 $v = json_decode($v,true);
                 $str = '';
-                if(count($v)>0){
+                if(!empty($v)&&count($v)>0){
                     foreach ($v as $item){
                         $str.='<img data-action="preview-img" src="'.$item.'" style="max-width:50px;max-height:200px;cursor:pointer" class="img img-thumbnail">';
                     }