TypeScript error when using `S3Handler` type

[Gary Sassano]

Describe the bug
A clear and concise description of what the bug is.

To Reproduce
How to reproduce the behaviour:

const lambdaHandler: S3Handler = async (event: S3Event): Promise<void> => {
  await Promise.all(event.Records.map(processRecord));
};

export const handler = middy().use(eventNormalizer()).handler(lambdaHandler);

Argument of type 'S3Handler' is not assignable to parameter of type 'MiddyInputHandler<S3Event, any, Context>'.
  Types of parameters 'callback' and 'opts' are incompatible.
    Type 'MiddyHandlerObject' is not assignable to type 'Callback<void>'.
      Type 'MiddyHandlerObject' provides no match for the signature '(error?: string | Error | null | undefined, result?: void | undefined): void'.

Expected behaviour
A clear and concise description of what you expected to happen.

Environment (please complete the following information):

• Node.js: [e.g. 20]
• Middy: [e.g. 5.0.0]
• AWS SDK [e.g. 3.0.0]

Additional context
Add any other context about the problem here.

[will Farrell]

I think this was fix in the last release. If not, would you like to submit a PR?

[Gary Sassano]

@willfarrell If by "last release" you mean middy@5.2.5, that's not available on npm.

[Gary Sassano]

Duplicate of #1176

[Gary Sassano]

Reopening since the issue is still present on latest version.

[Naor Peled]

On it 🙏

[Gary Sassano]

I still get the error in 5.4.0

[Naor Peled]

Hey @garysassano,
using the current implementation the following two ways would work:

middy(lambdaHandler).use(eventNormalizer())

// OR

const lambdaHandler = async (event: S3Event, context: Context) => {
  await Promise.all(event.Records.map(async () => await Promise.resolve()))
}

const handler = middy<S3Event, void>().use(eventNormalizer()).handler(lambdaHandler)

regarding a fix for the above syntax that you've mentioned, I'm on it but it will take some time.

[Naor Peled]

Hey @garysassano,
I've created a PR to properly resolve this.
Waiting for Will to review and hopefully we'll merge this within the next few days.