CSV file got really weird name

[MartySyposz]

Wanted to continue viewing a file

• Dragged in video + detection file
• Dragged in CSV file
• Did something that made me need to make it writable
• Tried putting a "2" in front of the filename

In the end the file saved was called 2.org.chromium.not-a-real-type.E21DDB58-8522-40C1-BB49-AA020663F78A (no extension)

[reinhrst]

So it turns out this happens if you enter a filename without extension: https://chromium.googlesource.com/chromium/src/+/b26b7fa4324d8eca94faa11a5759e92075f411cb/components/remote_cocoa/app_shim/select_file_dialog_bridge.mm#472

Not sure if we can avoid it (cancel the save), but we can at least put up a warning if this happens....