Trying to get into latest snapshot, game doesn't launch after play is clicked. This is from launcher

---- YOU CAN CLOSE THIS LAUNCHER IF THE GAME STARTED OK ----
---- YOU CAN CLOSE THIS LAUNCHER IF THE GAME STARTED OK ----
---- YOU CAN CLOSE THIS LAUNCHER IF THE GAME STARTED OK ----
---- (We'll do this automatically later ;D) ----
Client> Exception in thread "main" java.lang.NoClassDefFoundError: net/minecraft/client/main/Main
Client> Caused by: java.lang.ClassNotFoundException: net.minecraft.client.main.Main
Client> at java.net.URLClassLoader$1.run(URLClassLoader.java:202)
Client> at java.security.AccessController.doPrivileged(Native Method)
Client> at java.net.URLClassLoader.findClass(URLClassLoader.java:190)
Client> at java.lang.ClassLoader.loadClass(ClassLoader.java:306)
Client> at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:301)
Client> at java.lang.ClassLoader.loadClass(ClassLoader.java:247)
Game ended with bad state (exit code 1)
Deleting /Users/hannahgalloway/Library/Application Support/minecraft/versions/13w23b/13w23b-natives-1370891711404473000