Steps to Reproduce:

    1. Choose "Delete App" in Settings > General > iPad Storage > Minecraft 
    2. Reinstall Minecraft from App Store. 
    3. Launch Minecraft 
    4. Choose Worlds > Create New
    5. Create New World using all default settings.
    6. "Generating World" screen starts. It gets to "Building Terrain" and Minecraft crashes.
    7. Now, try to relaunch Minecraft. It now crashes at 40% of loading on restart. The crash occurs every restart.

Observed Results:

• The game crashes while building the new world.
• After failing to build the new world, the game crashes on every restart.

Expected Results:

• The game should successfully create the new world and load it.
• Even if it failed to build the world, the game should not crash on every restart after the failed build.

Testing notes: 
1. The crash does not occur when joining a realm or server (unless world creation has previously been attempted).
2. This occurs whether signed in or not, whether multiplayer or not, and whether creative or survival.
3. After the world fails to create, MC crashes on every restart at 40% of loading. 
The following actions do NOT keep the post-failed-create crashes from happening:
    a) "Offload App" and reinstall
    b) Delete the partially-created-world folder in Minecraft/minecraftWorlds
The only way forward after the failed world creation is to delete the app completely and reinstall it.