I ran a search for "Animation Metadata" and did not return any results for this particular message.

Upon loading the game, with my resource pack, some, but not all animations return errors due to an Array out of bounds. Those particular textures will appear as missing (purple/black) when in game.

Error:
"Unable to parse animation metadata from minecraft:textures/blocks/redstone_block.png
java.lang.ArrayIndexOutOfBoundsException"

This was my texture pack converted with the Ender tool and it does work in 13w24a with out any errors. Only since 13w24b, some animations return this error.

Attached you will find the dump from the dev console after the game is launched with the resource pack loaded, one .png texture thats offending and its mcmeta file.