What I expected to happen was...:
I was flying away from the banners to find an area to set up a tutorial video on banners

What actually happened was...:
I flew into the air and turned around. I started to fly around looking for an area. Then the game gave me a crash (which I have attached).

Steps to Reproduce: - I don't know if this is why it happened, but this is what I did.
1. Place Banners with designs.
2. Break crafting table.
3. Fly up while turning.
4. Fly forward.
5. Turn right and fly around.
6. Expect crash.

Note: I downloaded the snapshot for the first time before I created the world and it happened. It said it thinks my .jar was modded, but it wasn't. Is this just because it was a snapshot?

Hope this helps!