Merge pull request #3687 from kliushnichenko/fix/empty-mono

fix empty mono

Author: jknack

modules/jooby-reactor/src/main/java/io/jooby/reactor/Reactor.java

@@ -55,7 +55,7 @@ public Route.Handler apply(@NonNull Route.Handler next) {
               // Return context to mark as handled
               return ctx;
             } else if (result instanceof Mono mono) {
-              mono.subscribe(
+              mono.defaultIfEmpty(ctx.getResponseCode()).subscribe(
                   value -> {
                     // fire after:
                     after(ctx, value, null);