fix(core): move multipart/mixed to end of accept headers

[JoviDeCroock]

Summary

Follow up to #3007

In React-Native-Fetch streaming isn't supported meaning that the inclusion of multipart/mixed can lead to errors. We move it to the end of the Accept headers to avoid running into this bug. This was reported on Discord.

Relates to facebook/react-native#27741

[kitten]

Just noting based on discussions off GitHub; This isn't an issue with React Native per se, however, GraphQL Yoga seems to match the first transport method in Accept that can be used to fulfil a request, rather than defaulting to the standard JSON response and using a multipart one as needed.

This means that Yoga seems to trigger a multipart response, which is unsupported on React Native, even when this isn't stricly necessary, failing requests on RN entirely.

[ericbf]

Is this part of a release?

[JoviDeCroock]

@ericbf above your comment there is a linked merged PR that indicates the version this is part of... #3108

[ericbf]

Ok, so that’s what that means. I was wondering if that corresponded to a release (like on npm). Thank you!

[ericbf]

Because we’re on "urql": "^4.0.0" and we’re seeing an accept header of multipart/mixed, application/graphql-response+json, application/graphql+json, application/json. Should I open a bug report?

[ericbf]

After scouring the docs some more, seems like it due to still having @urql/exchange-multipart-fetch in there from before migrating (painfully) to version 4. A migration guide would have been helpful... Is there one?

It’s also worth mentioning that the package was actually @urql/exchange-multipart-fetch, not @urql/multipart-fetch-exchange.

[kitten]

@ericbf Yes, there is one: #3114
If you have amy questions please instead however open a discussion thread here on GitHub or on Discord. And yes, the package name is a typo. Re. still seeing old headers, you likely haven't deduplicated @urql/core, because even with old exchanges, which are still compatible, you should try to always keep only one version in your bundle/app. The migration guide has instructions on deduplicating however