See tahoe-lafs/magic-folder#131

In Gridsync, this behavior affects the restore/download functionality for folders since, if a user attempts to download a folder that was previously active/syncing on Windows, they'll see an error dialog (containing, for example: TahoeCommandError: Database '\\?\C:\Users\User\AppData\Roaming\Gridsync\MyGrid\private\magicfolder_documents.sqlite' already exists; not overwriting)

To compensate for this, Gridsync should attempt to remove the corresponding sqlite file whenever a user deletes or stops syncing a folder on Windows (possibly stopping the tahoe daemon process first, if needed to release the file-lock).