_delete_attachment_theme_mod() │ WP 3.0.0

Checks an attachment being deleted to see if it's a header or background image.

If true it removes the theme modification which would be pointing at the deleted attachment.

Internal function — this function is designed to be used by the kernel itself. It is not recommended to use this function in your code.

No Hooks.

Return

null. Nothing (null).

Usage

_delete_attachment_theme_mod( $id );
$id(int) (required)
The attachment ID.

Changelog

Since 3.0.0 Introduced.
Since 4.3.0 Also removes header_image_data.
Since 4.5.0 Also removes custom logo theme mods.

_delete_attachment_theme_mod() code WP 6.5.2

wp-includes/theme.php 
function _delete_attachment_theme_mod( $id ) {
	$attachment_image = wp_get_attachment_url( $id );
	$header_image     = get_header_image();
	$background_image = get_background_image();
	$custom_logo_id   = get_theme_mod( 'custom_logo' );

	if ( $custom_logo_id && $custom_logo_id == $id ) {
		remove_theme_mod( 'custom_logo' );
		remove_theme_mod( 'header_text' );
	}

	if ( $header_image && $header_image == $attachment_image ) {
		remove_theme_mod( 'header_image' );
		remove_theme_mod( 'header_image_data' );
	}

	if ( $background_image && $background_image == $attachment_image ) {
		remove_theme_mod( 'background_image' );
	}
}