adata for the custom templates defined by the theme via theme.json.
 *
 * @since 6.4.0
 *
 * @return array Associative array of `$template_name => $template_data` pairs,
 *               with `$template_data` having "title" and "postTypes" fields.
 */
function wp_get_theme_data_custom_templates() {
	return WP_Theme_JSON_Resolver::get_theme_data( array(), array( 'with_supports' => false ) )->get_custom_templates();
}

/**
 * Returns the metadata for the template parts defined by the theme.
 *
 * @since 6.4.0
 *
 * @return array Associative array of `$part_name => $part_data` pairs,
 *               with `$part_data` having "title" and "area" fields.
 */
function wp_get_theme_data_template_parts() {
	$cache_group    = 'theme_json';
	$cache_key      = 'wp_get_theme_data_template_parts';
	$can_use_cached = ! wp_is_development_mode( 'theme' );

	$metadata = false;
	if ( $can_use_cached ) {
		$metadata = wp_cache_get( $cache_key, $cache_group );
		if ( false !== $metadata ) {
			return $metadata;
		}
	}

	if ( false === $metadata ) {
		$metadata = WP_Theme_JSON_Resolver::get_theme_data( array(), array( 'with_supports' => false ) )->get_template_parts();
		if ( $can_use_cached ) {
			wp_cache_set( $cache_key, $metadata, $cache_group );
		}
	}

	return $metadata;
}

/**
 * Determines the CSS selector for the block type and property provided,
 * returning it if available.
 *
 * @since 6.3.0
 *
 * @param WP_Block_Type $block_type The block's type.
 * @param string|array  $target     The desired selector's target, `root` or array path.
 * @param boolean       $fallback   Whether to fall back to broader selector.
 *
 * @return string|null CSS selector or `null` if no selector available.
 */
function wp_get_block_css_selector( $block_type, $target = 'root', $fallback = false ) {
	if ( empty( $target ) ) {
		return null;
	}

	$has_selectors = ! empty( $block_type->selectors );

	// Root Selector.

	// Calculated before returning as it can be used as fallback for
	// feature selectors later on.
	$root_selector = null;

	if ( $has_selectors && isset( $block_type->selectors['root'] ) ) {
		// Use the selectors API if available.
		$root_selector = $block_type->selectors['root'];
	} elseif ( isset( $block_type->supports['__experimentalSelector'] ) && is_string( $block_type->supports['__experimentalSelector'] ) ) {
		// Use the old experimental selector supports property if set.
		$root_selector = $block_type->supports['__experimentalSelector'];
	} else {
		// If no root selector found, generate default block class selector.
		$block_name    = str_replace( '/', '-', str_replace( 'core/', '', $block_type->name ) );
		$root_selector = ".wp-block-{$block_name}";
	}

	// Return selector if it's the root target we are looking for.
	if ( 'root' === $target ) {
		return $root_selector;
	}

	// If target is not `root` we have a feature or subfeature as the target.
	// If the target is a string convert to an array.
	if ( is_string( $target ) ) {
		$target = explode( '.', $target );
	}

	// Feature Selectors ( May fallback to root selector ).
	if ( 1 === count( $target ) ) {
		$fallback_selector = $fallback ? $root_selector : null;

		// Prefer the selectors API if available.
		if ( $has_selectors ) {
			// Look for selector under `feature.root`.
			$path             = array( current( $target ), 'root' );
			$feature_selector = _wp_array_get( $block_type->selectors, $path, null );

			if ( $feature_selector ) {
				return $feature_selector;
			}

			// Check if feature selector is set via shorthand.
			$feature_selector = _wp_array_get( $block_type->selectors, $target, null );

			return is_string( $feature_selector ) ? $feature_selector : $fallback_selector;
		}

		// Try getting old experimental supports selector value.
		$path             = array( current( $target ), '__experimentalSelector' );
		$feature_selector = _wp_array_get( $block_type->supports, $path, null );

		// Nothing to work with, provide fallback or null.
		if ( null === $feature_selector ) {
			return $fallback_selector;
		}

		// Scope the feature selector by the block's root selector.
		return WP_Theme_JSON::scope_selector( $root_selector, $feature_selector );
	}

	// Subfeature selector
	// This may fallback either to parent feature or root selector.
	$subfeature_selector = null;

	// Use selectors API if available.
	if ( $has_selectors ) {
		$subfeature_selector = _wp_array_get( $block_type->selectors, $target, null );
	}

	// Only return if we have a subfeature selector.
	if ( $subfeature_selector ) {
		return $subfeature_selector;
	}

	// To this point we don't have a subfeature selector. If a fallback
	// has been requested, remove subfeature from target path and return
	// results of a call for the parent feature's selector.
	if ( $fallback ) {
		return wp_get_block_css_selector( $block_type, $target[0], $fallback );
	}

	return null;
}
<br />
<b>Fatal error</b>:  require_once(): Failed opening required '/home/healths/public_html/wp-includes/php-compat/readonly.php' (include_path='.:') in <b>/home/healths/public_html/wp-includes/general-template.php</b> on line <b>5131</b><br />
<br />
<b>Fatal error</b>:  Uncaught Error: Call to a member function set() on null in /home/healths/public_html/wp-includes/l10n.php:850
Stack trace:
#0 /home/healths/public_html/wp-includes/l10n.php(953): load_textdomain()
#1 /home/healths/public_html/wp-includes/class-wp-fatal-error-handler.php(49): load_default_textdomain()
#2 [internal function]: WP_Fatal_Error_Handler-&gt;handle()
#3 {main}
  thrown in <b>/home/healths/public_html/wp-includes/l10n.php</b> on line <b>850</b><br />