Missing argument for WP_Widget

I logged onto my site today and noticed that I am getting the following messages:

Warning: Missing argument 1 for WP_Widget::__construct(), called in /home2/gjhpus/public_html/wp-includes/class-wp-widget-factory.php on line 43 and defined in /home2/gjhpus/public_html/wp-includes/class-wp-widget.php on line 154

Warning: Missing argument 2 for WP_Widget::__construct(), called in /home2/gjhpus/public_html/wp-includes/class-wp-widget-factory.php on line 43 and defined in /home2/gjhpus/public_html/wp-includes/class-wp-widget.php on line 154

I can see the code in question, and it looks to me like it’s part of WP, not a plugin.

When I looked to see whether I had an outdated Plugin, I was very surprised to find that all my Plugins were up to date. I was even more surprised to see that the site was operating 4.4.1.

I got an email last week saying that my site had automatically been updated to 4.3.2. I didn’t get a message about upgrading to 4.4.1 so it’s possible this was done by one of the other administrators (I’m looking into that right now).

In the meantime, this is one of the two busiest years for our site. While it seems to be functioning, it’s disconcerting to see two lines of error messages everywhere we look. Any advice would be much appreciated.

The site in question is https://www.gjhp.org.

Many thanks!