fix restoring backups which were created without config.system (#1944)
fix restoring backups which were created without config.system (#1944)

* fix restoring backups which were created without config.system

- closes #1889

* code-optimization: simplify by conditional chaining
ioBroker/ioBroker.js-controller,ioBroker/ioBroker.js-controller,ioBroker/ioBroker.js-controller