Crash upon deleting feed

[Limfjorden]

Describe the bug
Vienna crashed after deleting a feed.

To Reproduce

1. I added a new feed, the URL of my Lemmy notification inbox.

2. I see that the feed does not work

3. I delete the feed

4. Vienna crashes

5. When I open Viena again, the feed is deleted.

Screenshots
Add screenshots to help explain your problem, if possible.

Please complete the following information:

• Vienna version: 3.8.8
• OS version: macOS 13.5.2

Additional information:
Here is the log: https://pastebin.com/gTF6s5CA

[Eitot]

The crash report unfortunately does not give a lot of information to find the cause of the crash. It seems to have something to do with the sidebar (NSOutlineView) and its textDidEndEditing: method. Notifications (NSNotification) are involved as well. Perhaps the text field of the feed item in the sidebar was in "edit mode" while it was deleted?

I am not sure if it is worthwhile diagnosing this further, as significant changes have been made to the sidebar code in 3.9.0 (a beta is available). The textDidEndEditing: method, for example, is no longer used.