Unable to launch game

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