respond with http status 500 upon error

src/gossa.go

@@ -57,6 +57,7 @@ func check(e error) {
 func exitPath(w http.ResponseWriter, s ...interface{}) {
 	if r := recover(); r != nil {
 		log.Println("error", s, r)
+		w.WriteHeader(500)
 		w.Write([]byte("error"))
 	} else if *verb {
 		log.Println(s...)