In some instances, with specific settings, the world generator can crash while creating a world, leaving the Minecraft window open. The only trace of this is in the crash report and console. I am aware that there are other issues like this, crashes while creating worlds, but this one is different, and spammed about 500 lines of code. Here is the pastebin for the report:

http://pastebin.com/AhpHFEha

Here is the generator preset used:

{"coordinateScale":684.412,"heightScale":684.412,"lowerLimitScale":64.0,"upperLimitScale":2.0,"depthNoiseScaleX":200.0,"depthNoiseScaleZ":200.0,"depthNoiseScaleExponent":0.5,"mainNoiseScaleX":80.0,"mainNoiseScaleY":160.0,"mainNoiseScaleZ":80.0,"baseSize":8.5,"stretchY":12.0,"biomeDepthWeight":1.0,"biomeDepthOffset":0.0,"biomeScaleWeight":1.0,"biomeScaleOffset":0.0,"seaLevel":6,"useCaves":true,"useDungeons":true,"dungeonChance":50,"useStrongholds":true,"useVillages":true,"useMineShafts":true,"useTemples":true,"useRavines":true,"useWaterLakes":true,"waterLakeChance":90,"useLavaLakes":true,"lavaLakeChance":10,"useLavaOceans":false,"fixedBiome":-1,"biomeSize":5,"riverSize":1,"dirtSize":33,"dirtCount":10,"dirtMinHeight":0,"dirtMaxHeight":256,"gravelSize":33,"gravelCount":8,"gravelMinHeight":0,"gravelMaxHeight":256,"graniteSize":33,"graniteCount":10,"graniteMinHeight":0,"graniteMaxHeight":80,"dioriteSize":33,"dioriteCount":10,"dioriteMinHeight":0,"dioriteMaxHeight":80,"andesiteSize":33,"andesiteCount":10,"andesiteMinHeight":0,"andesiteMaxHeight":80,"coalSize":17,"coalCount":10,"coalMinHeight":0,"coalMaxHeight":128,"ironSize":9,"ironCount":10,"ironMinHeight":0,"ironMaxHeight":64,"goldSize":9,"goldCount":2,"goldMinHeight":0,"goldMaxHeight":32,"redstoneSize":8,"redstoneCount":4,"redstoneMinHeight":0,"redstoneMaxHeight":16,"diamondSize":8,"diamondCount":1,"diamondMinHeight":0,"diamondMaxHeight":16,"lapisSize":7,"lapisCount":1,"lapisCenterHeight":16,"lapisSpread":16}