I tried to make a superflat world, where the custom preset is set to only generate one layer of fire. After generating and loading the world, the client crashed, and this is the crashlog:
---- Minecraft Crash Report ----
Time: 31-10-12 20:00
Description: Exception in server tick loop
... and so on.
- Minecraft Version: 1.4.2
- Operating System: Windows 7 (amd64) version 6.1
- Java Version: 1.7.0_07, Oracle Corporation
- Java VM Version: Java HotSpot(TM) 64-Bit Server VM (mixed mode), Oracle Corporation
- Memory: 327751592 bytes (312 MB) / 681705472 bytes (650 MB) up to 954466304 bytes (910 MB)
- JVM Flags: 2 total; -Xms512m -Xmx1024m
- AABB Pool Size: 11 (616 bytes; 0 MB) allocated, 0 (0 bytes; 0 MB) used
- Is Modded: Probably not
- Profiler Position: N/A (disabled)
- Vec3 Pool Size: 1 (56 bytes; 0 MB) allocated, 0 (0 bytes; 0 MB) used
- Player Count: 1 / 8; [ih['zenyl'/0, l='Test', x=-379,50, y=0,62, z=-731,50]]
- World Test Entities: 0 total; 
- World Test Players: 0 total; 
- World Test Chunk Stats: ServerChunkCache: 0 Drop: 0
- Type: Integrated Server
What I expected to happen was that the client would crash, which is what I got.
What actually happened was that the client crashed
Describe what happened here
Steps to Reproduce:
1. Make a custom preset for a superflat world, but only with 1 layer, of fire (51).
2. Let it load (takes some time)
3. Client crash.
This is, of course, a minor bug, but since you guys asked for bugs...