Combined with Catalyst's very talkative error trace, I get tons and tons of nonsense, and no useful information. In this case I was told that the problem was that there was an earlier transaction with problems. Well doh! Not very interesting. Tell me why you die, please.
Another thing about DBIC seems to be that
$schema is utterly useless after a failed
txn_do. You can get a resultset, see the classname, resoultsource etc. But don't you dare! to find some data. Why? Well, I don't know.