File::XML small improvement for unimarc guys

Hello world,

at line 503 is written :
die "Unsupported UNIMARC charater encoding [$enc] for XML output";

could we set instead :
die "Unsupported UNIMARC charater encoding [$enc] for XML output for $f, 
field 100 being ".$r->subfield(100 => 'a');

That would ease a lot debugguing erroneous MARC records...

-- 
Paul POULAIN et Henri Damien LAURENT
Consultants indépendants en logiciels libres et bibliothéconomie 
(http://www.koha-fr.org)
Tel : 04 91 31 45 19