Figuring out which command failed

Hi,

I have a transaction that has multiple separate command in it (nothing
unusual there).

However sometimes one of the sql statements will fail and so the whole
transaction fails.

In some cases I could fix the failing statement if only I knew which one
it was.  Can anyone think of any way to get which statement actually
failed from the error message?  If the error message gave me the line of
the failure it would be excellent, but it doesn't.  Perhaps it would be
easy for me to patch my version of Postgres to do that?

I realize I could do this with 2 phase commit, but that isn't ready yet!

Any thoughts or ideas are much appreciated

Thanks
Ralph