fix(commission/agent): 修复非图片类型字段空值校验逻辑

addons/shopro/controller/commission/Agent.php

@@ -101,7 +101,7 @@ class Agent extends Commission
             foreach ($form as &$item) {
                 if (!empty($data[$item['name']])) {
                     $item['value'] = $data[$item['name']];
-                } else {
+                } else if ($item['type'] !== 'image') {
                     $this->error($item['name'] . '不能为空');
                 }
             }