Whenever I try to enter Minecraft with 14w11b or 14w11a, it just crashes the game.

Whenever I try to enter Minecraft with 14w11b or 14w11a, it just crashes the game because there was no ".json" for cactus. When I opened my versions and opened the launcher for 14w11b with 7-zip, and looked in the block models, it showed the cactus. BTW, I have no resource packs on.