fix: handle missing route options (#236)

* fix: handle missing route options

* fix: support 4.0 version without routeOptions at all

* chore: return fastify version back

* refactor: get req config w/o function

* refactor: use optional chaining to get config

* refactor: remove extra ?. operator

index.js

@@ -221,7 +221,8 @@ async function fastifyUnderPressure (fastify, opts) {
   }
 
   function onRequest (req, reply, next) {
-    const _pressureHandler = req.routeOptions.config.pressureHandler || pressureHandler
+    const config = req.routeOptions?.config ?? req.context.config
+    const _pressureHandler = config.pressureHandler || pressureHandler
     if (checkMaxEventLoopDelay && eventLoopDelay > maxEventLoopDelay) {
       handlePressure(_pressureHandler, req, reply, next, TYPE_EVENT_LOOP_DELAY, eventLoopDelay)
       return