Reply.from inside async handler cause Promise may not be fulfilled with 'undefined' when statusCode is not 204

[ngkhnam]

🐛 Bug Report

when using reply.from inside async request handler will cause error "Promise may not be fulfilled with 'undefined' when statusCode is not 204"

To Reproduce

Steps to reproduce the behavior:
the handle code:
/node_modules/fastify/lib/wrapThenable.js:30:30

 `server.get('/', async (req, reply) => {
            //...some code here
            reply.from('<other url>');
});`

Expected behavior

no error message

Your Environment

• node version: 10
• fastify version: 3.6.0
• os: Mac
• any other relevant information

[mcollina]

you should do return reply at the end.

[ngkhnam]

thank @mcollina

[SimenB]

Can that be added to the error message somehow?

Is the general rule that if you do reply.* that handles the request (like reply.redirect or reply.from) in an async handler that you should always return it?

[mcollina]

Can that be added to the error message somehow?

Yes, definitely. On this topic there is fastify/fastify#2860 if you want to refactor that area of Fastify.