build: export NullProtoObj

Author: pi0

src/index.ts

@@ -7,3 +7,5 @@ export { findRoute } from "./operations/find.ts";
 export { removeRoute } from "./operations/remove.ts";
 export { findAllRoutes } from "./operations/find-all.ts";
 export { routeToRegExp } from "./regexp.ts";
+
+export { NullProtoObj } from "./_utils.ts";