[Unison-hackers] Unison crash

[Matthew Alford]

I've used unison for a long time now and have never encountered this  
error.  I'm syncing a directory on two local external drives under  
macos 10.4.  I'm using unison 2.27.55.  Both are formatted macos  
extended.  When I try to sync the volumes it goes and checks all  
files on both disks but then comes back with the error in a window:

Uncaught exception: *** -[NSCFArray objectAtIndex:]: index (0) beyond  
bounds (0)

Any ideas?

Thanks,
Matthew