WordPress Version: 6.1
/**
* Registers a settings error to be displayed to the user.
*
* Part of the Settings API. Use this to show messages to users about settings validation
* problems, missing settings or anything else.
*
* Settings errors should be added inside the $sanitize_callback function defined in
* register_setting() for a given setting to give feedback about the submission.
*
* By default messages will show immediately after the submission that generated the error.
* Additional calls to settings_errors() can be used to show errors even when the settings
* page is first accessed.
*
* @since 3.0.0
* @since 5.3.0 Added `warning` and `info` as possible values for `$type`.
*
* @global array[] $wp_settings_errors Storage array of errors registered during this pageload
*
* @param string $setting Slug title of the setting to which this error applies.
* @param string $code Slug-name to identify the error. Used as part of 'id' attribute in HTML output.
* @param string $message The formatted message text to display to the user (will be shown inside styled
* `<div>` and `<p>` tags).
* @param string $type Optional. Message type, controls HTML class. Possible values include 'error',
* 'success', 'warning', 'info'. Default 'error'.
*/
function add_settings_error($setting, $code, $message, $type = 'error')
{
global $wp_settings_errors;
$wp_settings_errors[] = array('setting' => $setting, 'code' => $code, 'message' => $message, 'type' => $type);
}