https://bugzilla.wikimedia.org/show_bug.cgi?id=66619
--- Comment #17 from Maarten Dammers maarten@mdammers.nl --- I was thinking. Both cases might be mixed depending on what module is throwing the error. Maybe we should grab ['error']['messages'] and check if it's a list or a dict and depending on that, grab the message.
That way we don't care any more about the format, we just accept both formats.