The following small change deals with a strange background-music-related crash. Wasn't this issue fixed for Jaitsu and Aether II? I'm not sure what's the cause but I've added a check to prevent the NPE. Please deal with this most robustly in the future.
DimDoors
Dimensional Doors for Minecraft Adds several items that allow the player to move between and create dimensions
see the MC forum topic for details