Log a warning when signal is already registered

index.js

@@ -25,12 +25,7 @@ function fastifyGracefulShutdown(fastify, opts, next) {
  for (let i = 0; i < signals.length; i++) {
  let signal = signals[i]
  if (handlerEventListener.listenerCount(signal) > 0) {
- next(
- new Error(
- `${signal} handler was already registered use fastify.gracefulShutdown`,
- ),
- )
- return
+ logger.warn(`${signal} handler was already registered. Ensure a controlled shutdown`)
  }
  }