I guys. I'd like to share my experience using Step Functions. If you write a async function, you can return its result without resolve it using await. Just do something like that:

export function handler (event: any) {
  return myAsyncFunction(event)
}

But, when working with a synchronous function (that does not return a Promise) is necessary to use something like that:

import { Callback, Context } from 'aws-lambda';

export function handler (event: any, context: Context, callback: Callback) {
  const output = mySyncFunction(event)
  callback(null, output)
}

If you try to return the result directly, you will get a null input in the next step.

In the second example you can mark the function

async

and you should just be able to return

output

Nice trick! Thanks

Or if the linter complains about a async definition on a function that doesn't contain an await you can return Promise.resolve(output)