I think you guys have veered off into the weeds with this. The current
solution - modulo error messages not destined for humans :) - is not soo
bad, considering the whole MCA trainwreck.

Or am I missing something completely unacceptable?

Maybe the other difference in approach between Andy and me is whether to
go for a solution that covers all the corner cases, or just make an incremental
improvement that allows for recover in some useful subset of remaining fatal
cases, but still dies in other cases.

I'm happy to replace error messages with ones that are more descriptive and
helpful to humans.

-Tony