Errors in logs

Hello,
When your plugin is activated with Email Template Customizer for Woocommercerce, i have a lot of errors :
[Tue Feb 09 07:15:23.172232 2021] [proxy_fcgi:error] [pid 24580] [client 123.201.58.179:48257] AH01071: Got error ‘PHP message: PHP Warning: DOMXPath::query(): Invalid expression in /home/lachaiseaguy/www/www.lachaiseaguy.fr/htdocs/wp-content/plugins/woocommerce/vendor/pelago/emogrifier/src/Emogrifier.php on line 494\nPHP message: PHP Warning: Invalid argument supplied for foreach() in /home/lachaiseaguy/www/www.lachaiseaguy.fr/htdocs/wp-content/plugins/woocommerce/vendor/pelago/emogrifier/src/Emogrifier.php on line 503\n’, referer: https://www.lachaiseaguy.fr/wp-admin/post.php?post=30384&action=edit&classic-editor

As I don’t know wich of both is the cause, I also send a message to the dev of the other plugin.

In your, in System status, I can read :
file_gets_content : ok
allow url open : seems to be not ok. Is it necessary ?

Thanks a lot for your reply