Any particular sort of bug that just happened?

Well, there's a bug that made me think about cause and effect, but it's not entirely related to this particular pattern. It's just that combining event handlers as functions would make me pass the db explicitly, making me notice that I actually don't have the db in the right state at the right time. Trying to drive the important parts of the app's state with the URL. The tricky part is that the way I have to parse most of the query parameters depends on the URL path and on some specific query parameters.