PHP7.4.33 → PHP8.1.22に上げたら、新規投稿・編集時に次のようなエラーメッセージが出るようになりました。

[Sat Nov 11 15:45:37.321917 2023] [proxy_fcgi:error] [pid 20960:tid 21063] [client 58.70.40.224:49146] AH01071: Got error 'PHP message: PHP Warning: Undefined array key "is_top" in /public_html/wp-content/themes/sango-theme/library/gutenberg/dist/classes/Conditional.php on line 58PHP message: PHP Warning: Undefined array key "is_category_top" in /public_html/wp-content/themes/sango-theme/library/gutenberg/dist/classes/Conditional.php on line 59PHP message: PHP Warning: Undefined array key "is_top" in /public_html/wp-content/themes/sango-theme/library/gutenberg/dist/classes/Conditional.php on line 58PHP message: PHP Warning: Undefined array key "is_category_top" in /public_html/wp-content/themes/sango-theme/library/gutenberg/dist/classes/Conditional.php on line 59PHP message: PHP Warning: Undefined array key "is_top" in /public_html/wp-content/themes/sango-theme/library/gutenberg/dist/blocks/content-block.php on line 89', referer: https://*****.com/wp-admin/post.php?post=11646&action=edit

[Sat Nov 11 15:45:37.447368 2023] [proxy_fcgi:error] [pid 20960:tid 21139] [client 58.70.40.224:49182] AH01071: Got error 'PHP message: PHP Warning: Undefined array key "is_top" in /public_html/wp-content/themes/sango-theme/library/gutenberg/dist/blocks/content-block.php on line 89', referer: https://*****.com/wp-admin/post.php?post=11646&action=edit

[Sat Nov 11 15:45:38.655615 2023] [proxy_fcgi:error] [pid 20960:tid 21140] [client 58.70.40.224:49590] AH01071: Got error 'PHP message: PHP Warning: Undefined array key "is_admin" in /public_html/wp-content/themes/sango-theme/library/gutenberg/dist/classes/Toc.php on line 113PHP message: PHP Warning: Undefined array key "is_category_top" in /public_html/wp-content/themes/sango-theme/library/gutenberg/dist/classes/Toc.php on line 118PHP message: PHP Warning: Undefined array key "is_top" in /public_html/wp-content/themes/sango-theme/library/gutenberg/dist/classes/Toc.php on line 125PHP message: PHP Warning: Undefined array key "is_admin" in /public_html/wp-content/themes/sango-theme/library/gutenberg/dist/classes/Toc.php on line 113PHP message: PHP Warning: Undefined array key "is_category_top" in /public_html/wp-content/themes/sango-theme/library/gutenberg/dist/classes/Toc.php on line 118PHP message: PHP Warning: Undefined array key "is_top" in /public_html/wp-content/themes/sango-theme/library/gutenberg/dist/classes/Toc.php on line 125', referer: https://*****.com/wp-admin/post.php?post=11646&action=edit