Brent Yorgey wrote:

It must be a problem with the ID3 implementation itself.  'items' is obviously not empty.  So the error must be coming from one of the calls to 'head' in the ID3 implementation (of which there are several).  The original author (whoever they were) ought to be ashamed of him/herself.  Having bugs in your implementation is excusable, but using functions like 'head' which can crash is not! ;) 

Thanks for confirming this. I think it's best not to waste any more time on this. I appreciate your help in any case, AK