next.js

63825de4 - LayoutRouter: Support segment value of Promise<null> to asynchronously bail out and trigger a server patch (#59724)

LayoutRouter: Support segment value of Promise<null> to asynchronously bail out and trigger a server patch (#59724) If the data for a segment is missing when LayoutRouter renders, it initiates a lazy fetch to patch the cache. This is how all dynamic data fetching works in the pre-PPR implementation. For PPR, we won't use this mechanism anymore for regular navigations, but (at least for now) we will still use it as a fallback behavior if the server response does not match what we expected to receive. This commit adds support for asynchronously triggering a lazy fetch, by unwrapping the segment data promise inside LayoutRouter to check if it's missing. If so, it will trigger the lazy fetch mechanism. When PPR is not enabled this should not observably impact behavior. Closes NEXT-1893