won't save osm file

[dogshed@…]

To reproduce the bug:
Open JOSM.
Select a gpx file.
Select file, save as.
Leave it on "all files".
Type a filename without an extension.
Select save.
You get the bad extension message.
Any future attempts give the bad extension
message even if the extension is good.

[Gabriel Ebner <ge@…>]

Works fine for me; loaded a gpx file, tried to save it as "foo", got error, saved it as "foo.gpx", which worked.

Which JOSM version are you using?

[dogshed@…]

Replying to Gabriel Ebner <ge@gabrielebner.at>:

Works fine for me; loaded a gpx file, tried to save it as "foo", got error, saved it as "foo.gpx", which worked.

Which JOSM version are you using?

621

I was trying to save and osm file, and if I put a way in then
it seems to save. I'll play with it. Maybe I forgot a step.