Using a fresh Ubuntu installation (I did a fresh install recently) and without adding any torrent to Deluge, it doesn't crash (attempt 1). Then I added a new torrent to Deluge, started the download and tried to replicate this bug and it occurred (attempt 2). Then (3d attempt): I started Deluge again (it still downloads the torrent I added in attempt 2), and when quitting via File > Quit, the bug didn't occur again.
I'm not sure what's going on, but maybe you can figure it out...
I've just tried it:
Using a fresh Ubuntu installation (I did a fresh install recently) and without adding any torrent to Deluge, it doesn't crash (attempt 1). Then I added a new torrent to Deluge, started the download and tried to replicate this bug and it occurred (attempt 2). Then (3d attempt): I started Deluge again (it still downloads the torrent I added in attempt 2), and when quitting via File > Quit, the bug didn't occur again.
I'm not sure what's going on, but maybe you can figure it out...