[Fastify] Crash when registering a middleware that also registers middie

[ancyrweb]

Is there an existing issue that is already proposing this?

• [X] I have searched the existing issues

Is your feature request related to a problem? Please describe it

I'm trying to integrate @fastify/vite with NestJS, but both @fastify/vite & @nestjs/platform-fastify register middie. Which leads to a crash.

So far the solution I've found is to implement the following.

async function bootstrapNestJs() {
  const adapter = new FastifyAdapter({ logger: true });
  await adapter.register(FastifyVite as any, {
    ...
  });

  (adapter as any).isMiddieRegistered = true;

  const app = await NestFactory.create<NestFastifyApplication>(
    AppModule,
    adapter,
  );

  const server = app.getHttpAdapter().getInstance() as any;
  await server.vite.ready();
  await app.listen(3000);
}

Describe the solution you'd like

The simple patch would be to add an other flag to the FastifyAdapter constructor to mark middie as already registered. I can propose a PR if wanted.

Teachability, documentation, adoption, migration strategy

It's just an optional flag.

What is the motivation / use case for changing the behavior?

Required to setup Vite with NestJS.