Hello there @nevuproject!
This type of error has popped up around the commmunity in other threads, and it’s usually tied to your current shader setup, caused by incomplete or corrupted data.
The first step here is to verfy your UEFN install. Locate it in your library, open the dropdown menu, anc click on Verify. This should restore any missing elements in your setup. Afther that, re-launch the editor. If the issue persists, then the next step is to clear your shader cache. To do that, go to your Local app data directory, and delete the following folders:
…\FortniteGame\Saved
…\UnrealEngine\Common\DerivedDataCache
…\EpicGamesLauncher\Saved\
Once you are done, re-open UEFN, and allow it to rebuild the shaders (it will take some time). At this point, the crash should be resolved. If not, the remaining option we have is to fully reinstall UEFN.