Export browse can open in non-existent folder

[Oranjoose]

Godot 3.1 alpha 3
Windows 10 x64

If you export a project into a folder, and then delete that folder, then try to export the project again, then browse within the export dialog will open into the folder that had been deleted. If you then try to export the project within this non-existent folder, Godot fails out with a warning message that it couldn't write to the folder.

Maybe best to have Godot export browse dialog open to the next closest existing parent directory, or default to the root of the project folder if the last export folder is non-existent.

[qarmin]

Probably #22670 fix this