k but want idempotent

main.go

@@ -90,6 +90,7 @@ func main() {
 	log.Println("listening on", *p)
 	if err := http.ListenAndServe(":"+strconv.Itoa(*p), http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 		if err := handle(w, r); err != nil {
+			log.Println("!", err)
 			http.Error(w, err.Error(), http.StatusBadRequest)
 		}
 	})); err != nil {