Superflat overworld preset not working

Whenever I try and load a superflat world with the preset "overworld", the game crashes and I get the error message "The game crashed whilst mouseclicked event handler
Error: java.lang.NullPointerException: mouseClicked event handler". This doesn't happen when I try and load a 'normal' superflat world or just a normal world. How can I fix this? or is it just a bug within the snapshot?