[Resolved] rtrim(): Passing null to parameter #1 ($string) of type string is deprecated

Hi,

After updating, and once activated, WPML spams this error on our staging, but not on the local env (count 112 on the plugins.php page):

rtrim(): Passing null to parameter #1 ($string) of type string is deprecated

Stack trace:
wp-includes/formatting.php:2809
rtrim()
wp-includes/formatting.php:2809
untrailingslashit()
wp-includes/formatting.php:2794
trailingslashit()
app/plugins/sitepress-multilingual-cms/classes/url-handling/class-wpml-include-url.php:27
WPML_Include_Url->filter_include_url()
wp-includes/class-wp-hook.php:310
apply_filters('style_loader_src')
wp-includes/class-wp-styles.php:412
WP_Styles->_css_href()
wp-includes/class-wp-styles.php:221
WP_Styles->do_item()
wp-includes/class-wp-dependencies.php:137
WP_Dependencies->do_items()
wp-includes/script-loader.php:2213
print_admin_styles()
wp-includes/class-wp-hook.php:308
do_action('admin_print_styles')
wp-admin/admin-header.php:132

Current version : Version 4.6.5
WP Version : 6.2.2

Only this plugin is activated, 2 languages domains are configured.

This appears to come from sitepress-multilingual-cms/classes/url-handling/class-wpml-include-url.php, in function filter_include_url where returns NULL.

Any fix would be appreciated.

For now, I just changed line 28 to this, but not sure it is actually the correct fix, not sure why I get a null value there, and I'm afraid the following fix will just hide unexpected behaviors.

if ( $php_host_in_domain && strpos( trailingslashit( $php_host_in_domain ), trailingslashit( $dom ) ) === 0 ) {

Any thought would be appreciated.

Regards.