WP_Theme_JSON_Resolver::get_file_path_from_theme( string $file_name )

Source

File: wp-includes/class-wp-theme-json-resolver.php

private static function get_file_path_from_theme( $file_name ) {
		/*
		 * This used to be a locate_template call. However, that method proved problematic
		 * due to its use of constants (STYLESHEETPATH) that threw errors in some scenarios.
		 *
		 * When the theme.json merge algorithm properly supports child themes,
		 * this should also fall back to the template path, as locate_template did.
		 */
		$located   = '';
		$candidate = get_stylesheet_directory() . '/' . $file_name;
		if ( is_readable( $candidate ) ) {
			$located = $candidate;
		}
		return $located;
	}