fix(http-server-js): send bytes body directly without JSON serialization

[snipd-mikel]

When an operation returns a bytes body with a custom @header contentType
(e.g. "application/zip"), the emitter was unconditionally overwriting the
content-type with "application/json" and calling the non-existent
Uint8Array.toJsonObject(), causing a runtime crash.

Add a isStdType(body.type, "bytes") check in emitResultProcessingForType
before the JSON serialization path — mirroring the equivalent check already
present on the request deserialization side (added in #6898) — so that binary
responses are written directly to the response stream with the content-type
already set by the @header property.

Fixes #10609

[snipd-mikel]

@microsoft-github-policy-service agree [company="Snipd AG"]

[snipd-mikel]

@microsoft-github-policy-service agree company="Snipd AG"

[pkg-pr-new]

Open in StackBlitz

npm i https://pkg.pr.new/@typespec/http-server-js@10610

commit: d7ba548

[github-actions]

❌ There is undocummented changes. Run chronus add to add a changeset or click here.

The following packages have changes but are not documented.

• ❌@typespec/http-server-js

Show changes

[witemple-msft]

@snipd-mikel I think this is an improvement over what we have now, but it's not always correct to treat bytes as raw bytes. In a JSON response, bytes are supposed to be encoded in a JSON string using base64.

There's also another more explicit way to declare an API that transmits a file if that's what you are looking to do (Http.File).

I appreciate the contribution, but I put up a PR that I think gets us a more accurate treatment of bytes as well as Http.File that I think should work for your usecase. Aside: I also added http-server-js to the TypeSpec playground. PR: #10799