I was flying around a new generated world and i randomly got this crash:
Hope to help.

---- Minecraft Crash Report ----
// I feel sad now

Time: 7/23/14 10:35 AM
Description: Tesselating block model

java.lang.IndexOutOfBoundsException: Index: 1, Size: 0
at java.util.ArrayList.rangeCheck(Unknown Source)
at java.util.ArrayList.get(Unknown Source)
at csu.b(SourceFile:88)
at chc.a(SourceFile:156)
at cjs.a(SourceFile:139)
at cjs.a(SourceFile:74)
at cjs.a(SourceFile:43)
at cjs.a(SourceFile:35)
at cjq.a(SourceFile:62)
at cmt.b(SourceFile:156)
at cmm.a(SourceFile:71)
at cmm.run(SourceFile:31)
at java.lang.Thread.run(Unknown Source)

A detailed walkthrough of the error, its code path and all known details is as follows:
---------------------------------------------------------------------------------------

– Head –
Stacktrace:
at java.util.ArrayList.rangeCheck(Unknown Source)
at java.util.ArrayList.get(Unknown Source)
at csu.b(SourceFile:88)
at chc.a(SourceFile:156)
at cjs.a(SourceFile:139)
at cjs.a(SourceFile:74)

– Block model being tesselated –
Details:
Block: minecraft:log2[axis=y,variant=dark_oak]
Block location: World: (495,64,102), Chunk: (at 15,4,6 in 30,6; contains blocks 480,0,96 to 495,255,111), Region: (0,0; contains chunks 0,0 to 31,31, blocks 0,0,0 to 511,255,511)
Using AO: true
Stacktrace:
at cjs.a(SourceFile:43)
at cjs.a(SourceFile:35)

– Block being tesselated –
Details:
Block type: ID #162 (tile.log // axe)
Block data value: 1 / 0x1 / 0b0001
Block location: World: (495,64,102), Chunk: (at 15,4,6 in 30,6; contains blocks 480,0,96 to 495,255,111), Region: (0,0; contains chunks 0,0 to 31,31, blocks 0,0,0 to 511,255,511)
Stacktrace:
at cjq.a(SourceFile:62)
at cmt.b(SourceFile:156)
at cmm.a(SourceFile:71)
at cmm.run(SourceFile:31)
at java.lang.Thread.run(Unknown Source)

– System Details –
Details:
Minecraft Version: 14w30a
Operating System: Windows 7 (amd64) version 6.1
Java Version: 1.8.0_05, Oracle Corporation
Java VM Version: Java HotSpot(TM) 64-Bit Server VM (mixed mode), Oracle Corporation
Memory: 4906628456 bytes (4679 MB) / 6203899904 bytes (5916 MB) up to 6203899904 bytes (5916 MB)
JVM Flags: 3 total; -XX:HeapDumpPath=MojangTricksIntelDriversForPerformance_javaw.exe_minecraft.exe.heapdump -Xmx6144M -Xms6144M
IntCache: cache: 0, tcache: 0, allocated: 13, tallocated: 95