[مغلق] Error message show on header

Background of the issue:
I was trying to access my WordPress site and encountered an error. The error message appeared on the header of the page. Here is the link to the page where the issue can be seen: الرابط المخفي. The specific error message is: Warning: Attempt to read property "count" on null in /var/www/vhosts/granddesignhk.com/health.granddesignhk.com/wp-includes/class-wp-term-query.php on line 852.

Symptoms:
An error message is displayed on the header of the page: 'Warning: Attempt to read property "count" on null in /var/www/vhosts/granddesignhk.com/health.granddesignhk.com/wp-includes/class-wp-term-query.php on line 852'.

Questions:
How can I resolve the error message appearing on the header?
What causes the 'Attempt to read property "count" on null' error?