Comment 2 for bug 1222132

I agree that exceptions should report errors from the proper thread.

However, making the "error_log" property thread specific might lead to funny results. You could then validate a document in one thread, pass the validator on to another for result processing, and it would report completely unrelated messages. Not different from what you currently get when you share it. Might be the lesser of two evils, but still not exactly a proper fix.