Include charset=utf-8 by default in application/json endpoints.

[coreh]

Hey there 👋

I was getting Mojibake when returning unicode data from my endpoints, so I checked the headers and noticed the charset=utf-8 option was missing from Content-Type. This in turn was causing the response to incorrectly be interpreted as Windows-1252.

This PR changes src/runtime/server/endpoint.js to include that by default for typeof body === 'object'.

I couldn't find any tickets about this, believe this change is simple enough that it's okay for me to open a PR without filing a ticket first.

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[benmccann]

It looks like there are some CI failures

[Conduitry]

Yep, this seems reasonable to do for responses that SvelteKit is automatically serializing.

The test failures look like just some content-type values in other tests that need to be updated to include the charset.

[coreh]

Sorry, it was quite late and my brain was foggy, I think I ran tests locally on the wrong directory. 🥶

I'll fix these after work, later today

[changeset-bot]

🦋 Changeset detected

Latest commit: c8cced1

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 1 package

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@sveltejs/kit	Patch

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[coreh]

@benmccann @Conduitry Fixed linting and the broken test.

I also removed the value check for the response body in c8cced1, since upon further digging it looks like the tests don't actually encode/decode the strings as byte buffers like a real HTTP implementation would, so it wasn't really testing anything.

[coreh]

Hey 👋

Let me know if you need me to make any additional changes or add more tests.

I can add back the test for UTF-8 encoding/decoding if there's a sanctioned way to make the HTTP response binary during the tests (or I can also try to figure out a mechanism for this if not present)