Server error at /feed endpoints

[vitormarcal]

The RSS feed endpoints gives a server error 500.

linkding | 2023-11-03 13:16:06,794 ERROR Internal Server Error: /feeds/some_id/unread
linkding | Traceback (most recent call last):
linkding | File "/opt/venv/lib/python3.10/site-packages/django/core/handlers/exception.py", line 56, in inner
linkding | response = get_response(request)
linkding | File "/opt/venv/lib/python3.10/site-packages/django/core/handlers/base.py", line 197, in _get_response
linkding | response = wrapped_callback(request, *callback_args, **callback_kwargs)
linkding | File "/opt/venv/lib/python3.10/site-packages/django/contrib/syndication/views.py", line 40, in call
linkding | feedgen = self.get_feed(obj, request)
linkding | File "/opt/venv/lib/python3.10/site-packages/django/contrib/syndication/views.py", line 191, in get_feed
linkding | description = self._get_dynamic_attr("item_description", item)
linkding | File "/opt/venv/lib/python3.10/site-packages/django/contrib/syndication/views.py", line 103, in _get_dynamic_attr
linkding | return attr(obj)
linkding | File "/etc/linkding/./bookmarks/feeds.py", line 35, in item_description
linkding | return sanitize(item.resolved_description)
linkding | File "/etc/linkding/./bookmarks/feeds.py", line 21, in sanitize
linkding | return ''.join(ch for ch in text if ch in valid_chars or unicodedata.category(ch)[0] != 'C')
linkding | TypeError: 'NoneType' object is not iterable
linkding | [pid: 17|app: 0|req: 303/464] 171.18.0.30 () {68 vars in 1335 bytes} [Fri Nov 3 13:16:06 2023] GET /feeds/some_id/unread => generated 145 bytes in 66 msecs (HTTP/1.1 500) 8 headers in 282 bytes (1 switches on core 1)

I think is related to #565