[BE] Expanding landing instead of trying to navigate to it works in all channels (that have it) but not in React CSR SPA

1. Open HAP and its sitemap – if you click on landing, it expands, no errors.
2. Open React CSR SPA, its sitemap, click on landing.

Expected behaviour: same as in HAP, expanding the landing node without navigating to it or throwing errors.
Actual behaviour: navigates to landing, shows Page 404.