errors when user denies permission

There are a few places where errors are lost when user denies permission. 

One is on the save file: https://github.com/enokidotsite/panel/blob/master/source/plugins/panel.js#L202. This is fixed by adding await:

```js
return await archive.writeFile(filePath, fileEncoded, encoder)
```

There was another, but can't remember at the moment. I'll add comment if I find again.