Check for missing download path

[dcposch]

Also handle the case where the user cancels out of Save Torrent File As

Fixes #646.

[feross]

good catch!

[feross]

This is good. One concern though: this only shows the user a message when the download folder is gone, but it doesn't prevent the active torrents from being added to the torrent engine, right? That means that webtorrent will make new directories, right? That's not what we want.

We should probably wait for the check to confirm the directory exists before adding to the torrent engine.

But, come to think of it, there's a bigger issue.

The default download path in Preferences is not necessarily the same as the torrents. The preference could have been changed to an external drive after several torrents were already started in ~/Downloads. In that case, the torrents that live in ~/Downloads should show up in the list and be usable by the user.

What do you think about changing this PR fs.stat the torrentSummary.path before calling webtorrent.add()? Torrents whose locations do not exist anymore could still show up in the list, but with warning text in their status line (below the name). This is what Transmission does.

As for the warning about the default download path being missing, I think that can stay. But I don't think it shouldn't prevent rendering of the entire torrent list when it's missing. What about just showing the warning at the top of the list?

[dcposch]

Ya, I just wanted to do the easy part first.

I can a per-torrent check similar to the one Transmission has.

[dcposch]

[dcposch]

@feross fixed. New error message

[feross]

LGTM -- we can work on improving the design of this and honing the copy in a future PR.

[dcposch]

[feross]

Released in WebTorrent Desktop v0.11!