Nitro Engine does not support Async Higher Order Functions

Environment

• Operating System: Darwin
• Node Version: v16.12.0
• Nuxt Version: 3.0.0-27252861.4f9c87b
• Package Manager: npm
• Bundler: Webpack
• User Config: vite
• Runtime Modules: -
• Build Modules: -

Describe the bug

Async Higher-Order Functions on API Routes are not supported always return a handle is not a function.

Reproduction

// api/graphql.ts

async function main() { return function () { return { hello: “World” }; }; }

export default main();

Additional context

No response

Logs

status code: 500

handle is not a function
  at file://./node_modules/h3/dist/index.mjs:111:24  
  at new Promise (<anonymous>)  
  at callHandle (file://./node_modules/h3/dist/index.mjs:108:10)  
  at file://./node_modules/h3/dist/index.mjs:104:12  
  at file://./node_modules/h3/dist/index.mjs:132:34  
  at processTicksAndRejections (node:internal/process/task_queues:96:5)  
  at async handle (file://./node_modules/h3/dist/index.mjs:572:19)

[pi0]

If you want to avoid top level await as mentioned in earlier example, try this:

import { lazyHandle } from 'h3'

export default lazyHandle(async () => {
  const apollo = await apolloServer.start()
  const handler = apollo.createHandler()
  return handler
})

[pi0]

This is nice with apollo-server-h3 💚

Nitro itself lazy loads API routes on the first call but we can do something like this:

const apolloServer = new ApolloServer({ typeDefs, resolvers })

export default apolloServer.start().then(() => apolloServer.createHandler)

Please don’t hesitate to DM me or open a discussion to continue this 😃