fix sandbox

Author: eunjae-lee

packages/sandbox/src/components/FieldPluginSandbox.tsx

@@ -252,6 +252,15 @@ const useSandbox = (
         action: 'asset-selected',
         callbackId: message.callbackId,
         filename: `${originFromPluginParams(pluginParams)}/icon.svg`,
+        fieldtype: 'asset',
+        name: '',
+        meta_data: {},
+        title: '',
+        copyright: '',
+        focus: '',
+        alt: '',
+        source: '',
+        is_private: false,
       })
     },
     [uid, pluginParams, dispatchAssetSelected],