I'll get a PR opened for a fix for this. I've tested it and a simple validation before the call is all that is needed.

Thank you for raising the issue @timnolte ! Can you provide a step to reproduce this issue? Cheers!

I'm getting the error:

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

Environment: WordPress 6.4.1 on PHP 8.1.25. The error appears both in the dashboard and on the front-end.

Here's a full stacktrace with identifying stuff redacted:

wp-includes/formatting.php:4494
ltrim()
wp-includes/formatting.php:4494
esc_url()
wp-includes/formatting.php:4620
sanitize_url()
wp-includes/formatting.php:4602
esc_url_raw()
wp-content/plugins/google-site-kit/includes/Core/Assets/Assets.php:716
Google\S\C\A\Assets->get_inline_base_data()
wp-content/plugins/google-site-kit/includes/Core/Assets/Assets.php:356
Google\S\C\A\Assets->Google\S\C\A{closure}()
wp-content/plugins/google-site-kit/includes/Core/Assets/Assets.php:356
Google\S\C\A\Script_Data->Google\S\C\A{closure}()
wp-content/plugins/google-site-kit/includes/Core/Assets/Script_Data.php:51
Google\S\C\A\Asset->before_print()
wp-content/plugins/google-site-kit/includes/Core/Assets/Assets.php:1016
Google\S\C\A\Assets->run_before_print_callbacks()
wp-content/plugins/google-site-kit/includes/Core/Assets/Assets.php:1025
Google\S\C\A\Assets->run_before_print_callbacks()
wp-content/plugins/google-site-kit/includes/Core/Assets/Assets.php:1025
Google\S\C\A\Assets->run_before_print_callbacks()
wp-content/plugins/google-site-kit/includes/Core/Assets/Assets.php:1025
Google\S\C\A\Assets->run_before_print_callbacks()
wp-content/plugins/google-site-kit/includes/Core/Assets/Assets.php:155
Google\S\C\A\Assets->Google\S\C\A{closure}()
wp-includes/class-wp-hook.php:324
do_action('wp_print_scripts')
wp-includes/script-loader.php:2214
wp_print_head_scripts()
wp-includes/class-wp-hook.php:324
do_action('wp_head')
wp-includes/general-template.php:3052
wp_head()
wp-content/themes/{theme}/header.php:20
load_template('wp-content/themes/{theme}/header.php')
wp-includes/template.php:725
locate_template()
wp-includes/general-template.php:48
get_header()
wp-content/themes/{theme}/singular.php:15

I'll note that this doesn't seem to be exactly the same as @timnolte's fix, so it's possible this error is in a few different places.

Here is my Site Kit info from Tools > Site Health with identifying stuff removed

@mrwweb Thanks for your comment. We don't provide support via GitHub but we'd be delighted to assist you with this in the Site Kit support forum. Please can you open a new support topic and share the details you have done so here. Thanks and we look forward to helping you with this!

@adamdunnage this isn't in need of some additional support forum request. This is a code issue that needs to be fixed, which I already provided a PR to fix this. The output that @mrwweb provided are the details to traceback this depreciation notice. This is a PHP 8.1 compatibility issue not an end user issue.

@mrwweb just noticed that your stack trace does appear to call out the ltrim() in WordPress Core. Have you taken a look at the code called out in each line of the stack trace? If not I can take a look to determine if I can update my PR to include fixing this as well. I'm suspecting that this may be partly do an incomplete plugin setup, and there isn't adequate validation happening.

@timnolte Haven't done anything else. I saw the error, found this issue, and saw the request for a stacktrace and dumped it here. Hope it's useful!

This issue still exists in Site Kit. I get the deprecation warning in both PHP 8.1 and 8.2 on every page load with stack trace results like originally reported.

@kevinlisota Yes, this issue remains open at the moment, but it's on our list to fix in a future release. Feel free to follow along here for updates. Thanks!