Closed Crash to desktop upon killing Kluex

I've got a crash to desktop right as Kluex's life bar reached 0. It doesn't happen in 100% of the cases, as my next attempt worked fine.

See the log in attachment.

The cause seems to be this:
[01:01:48.444] [Error] Application: exception thrown, shutting down: (AssetException) Error loading asset /monsters/boss/kluexboss/kluexboss.png:yellow.spinwindup.1

After poking around the data files, it seems that somehow, the boss found itself in "yellow" state (fire attack) and launched the "spinwindup" animation state, which doesn't exist in the yellow state. Looking at the behavior file closely, it seems the "spinwindup" state is not supposed to happen while still in the yellow state yet it somehow did, but I'm not familiar with SB's behavior system so I probably missed something.

However, when it crashed the boss was in its fire attack phase (or perhaps just finishing it, I don't remember exactly). On my subsequent attempt that didn't crash, I killed it during an ice attack phase, if it's any help.