"Update Data" opens a new .osm layer if one doesn't exist already
|Reported by:||avar||Owned by:||team|
Steps to reproduce:
- Start JOSM
- File->Update Data
- JOSM will show a "No data to update found" and open a new anonymous .osm layer
Instead it should just display a message indicating that no data is loaded and leave the user at the motd screen.