TypeError [ERR_INVALID_ARG_TYPE]: The "transform.writable" property must be an instance of WritableStream. Received an instance of Sharp about sharp

[antony]

Gotcha! This must have changed between node 16 and 20 which is why I suddenly ran into it.

I did see that there were two distinct types of stream, but the error thrown by node doesn't indicate the two types, but instead that the arg is a Sharp which masks the real issue!

Thank you for looking into this :)

Update: Example now works: https://stackblitz.com/edit/sveltejs-kit-template-default-ea5vps?file=src%2Froutes%2F%2Bserver.js

[lovell]

Hi Antony, great to meet you too.

The body property provided by fetch() is a ReadableStream, which is somewhat confusingly part of the Web API rather than the Node.js Stream API. You can convert it to a Readable (i.e. a Node.js Stream) using Readable.fromWeb().

-   const resizedImage = imageRes.body.pipeTo(transformer);
+   const resizedImage = Readable.fromWeb(imageRes.body).pipe(transformer);

I'll add an example to the docs as I suspect you won't be the only person who runs into this.

[lovell]

Commit 045d54e modernises one of the existing examples in the docs to include use of fetch() and .fromWeb().