Log warning if handler function returns no status code

[PetrGlad]

Improvement, additional validation. If handler returns empty response (e.g. nil) no response status is available for statistic's metrics. This causes confusing statistic's metrics like 'some.id..POST' while ''some.id.200.POST'' is expected. I suggest log a warning in this case to help with diagnostics.

Probably this can be implemented as separate middleware but I think simplest ways is just to check this directly in add-metrics-filter inside (swap! status (fn [_] (.getStatus (cast HttpServletResponse response))))

[LappleApple]

Hi @dryewo, any plans to do something here? Maybe @PetrGlad could take it, or we could add a "Help Wanted" label.