File write error: undefined

The command `Page.cmd "fileWrite"` is showing a UI message error with the text: `File write error: undefined` but there is nothing in the debug logs nor console.

**To Reproduce:**

1 - Download the site Antilibrary.bit and add the spanish DB (just because it is the smallest one)
2 - Import this CSV ([goodreads_library_export.txt](https://github.com/HelloZeroNet/ZeroNet/files/627852/goodreads_library_export.txt)) on the Goodreads CSV Importer in Antilibrary.bit (inside My Books)

The file will import and you should get this error after 2 or 3 seconds.
I can't find a way to debug this problem because it seems that this error is showing just in the UI.