[PATCH] WIP: pass through errors to structured output
like the subject says, work in progress.
The idea is to include an optional error reporting dictionary in
structured output to help clients figure out wth went wrong without
attempting to parse stderr. It's a new key so it shouldn't break sane
clients. Or even notmuch-emacs ;).
Some things to complete/bikeshed.
- some of the names are clearly terrible. "message", I'm looking at you.
- make most of the NULL returns here return a node with some
- possibly still print to stderr for non-structured formats.
- maybe think about a future consolidation of all of the status info