The game crashes when creating a superflat world

The game crashes when creating a superflat world. Can you fix this bug?

What I expected to happen was...:
In the past versions (1.3 or lower), I create superflat worlds
without the game crashes.

What actually happened was...:
After the 1.4 update was released, I tried to create another
superflat world, then, the screen "Building Terrain" shows up so long
and I realized, it crashed. Please fix this bug. My friends also having this bug.