Allow the preview and config screens to work with world generators that require asset loading (like the Heightmap).  Fix the preview world screen to reset when opening with a different generator selected (it was never reinitializing with the new generator).  Finally,  does not crash the game when a world generator does not play nice with the preview window.
Add logging for cases where world preview generation fails on a specific layer.
Fix conflict - crash issue was addressed differently by two different PRs