public function validate_path( $path ) {
		$result = null;

		$path = (string) $path;

		// Empty values are not valid.
		if ( empty( $path ) ) {
			return 'Empty path is not allowed';
		}

		// Path must not end in slash.
		// As per https://codex.wordpress.org/Function_Reference/register_theme_directory .
		if ( DIRECTORY_SEPARATOR === substr( $path, -1, 1 ) ) {
			return "Path ends in slash [$path]";
		}

		return $result;
	}