wp_trigger_error( string $function_name, string $message, int $error_level = E_USER_NOTICE )

function wpdocs_get_price_html( $post_id ) {
	$price = get_post_meta( $post_id, 'price', true );

	if ( '' === $price ) {
		wp_trigger_error(
			__FUNCTION__,
			'No <code>price</code> meta was found for post ID ' . absint( $post_id ) . ', returning an empty string.'
		);
		return '';
	}

	return '$' . esc_html( $price );
}

if ( ! defined( 'WP_DEBUG' ) || ! WP_DEBUG ) {
	echo esc_html( 'WP_DEBUG is off in this sandbox, so wp_trigger_error() returns immediately and never reaches trigger_error().' );
} else {
	set_error_handler(
		function ( $errno, $errstr ) {
			echo esc_html( 'PHP notice raised: ' . $errstr );
			return true;
		}
	);

	// Post 2 already has `price` meta, post 3 does not, so only post 3 triggers the notice.
	echo esc_html( 'Post 2: ' . wpdocs_get_price_html( 2 ) . ' | ' );
	echo wpdocs_get_price_html( 3 );

	restore_error_handler();
}
When	Instructions	Calls it makes
always	6	none
`$error_level === 256`	25–29	`do_action(), wp_kses()`
`$error_level !== 256`	26–30	`do_action(), wp_kses(), trigger_error()`
PHP	Compiled	Executed	Branches	Notes
8.6-dev	35	6–30	3
8.5	35	6–30	3
8.4	35	6–30	3	2 fewer instructions than PHP 8.3
8.3	37	6–32	3
8.2	37	6–32	3
8.1	37	6–32	3
7.4	37	6–32	3