修复文件上传表单删除文件时报destroyThumbnail不存在问题

src/Form/Field/UploadField.php

@@ -394,7 +394,9 @@ trait UploadField
             return;
         }
 
-        $this->destroyThumbnail($paths);
+        if (method_exists($this, 'destroyThumbnail')) {
+            $this->destroyThumbnail($paths);
+        }
 
         $storage = $this->getStorage();