fix: Can no longer access header values sent through JSON helper via loaderHeaders.get

[himorishige]

I modified the header values sent by the JSON helper to be accessible via loaderHeaders.get

close #1140

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[ryanflorence]

You mind writing a test for this? I'm unclear on how the bug surfaces, and why this fixes it.

I'd expect the fix to be in the json helper or the code that calls headers.

[ryanflorence]

Please see the comments on #1140

[himorishige]

Thanks for reviewing it.
I reverted and fixed the code.

2241639

I'm hoping that in my environment, the header will be no-store.
However, it seemed that max-age... was displayed.

remix 1.1.3

import { HeadersFunction, json, LoaderFunction } from 'remix';

export const headers: HeadersFunction = ({ loaderHeaders }) => {
  console.log(loaderHeaders.get('Cache-Control'));  // return null
  const cacheControl =
    loaderHeaders.get('Cache-Control') ??
    'max-age=0, s-maxage=60, stale-while-revalidate=60';
  return {
    'Cache-Control': cacheControl,
  };
};

export const loader: LoaderFunction = async () => {
  return json(null, { headers: { 'Cache-Control': 'no-store' } });
};

export default function PostsId() {
  return <div className="prose p-4">text</div>;
}

https://codesandbox.io/s/intelligent-sammet-losgp?file=/app/routes/index.tsx

[ryanflorence]

Ah we have regression here, at the moment, headers incorrectly requires that every parent route has a loader. We'll fix this soon, thanks for your work on this :)

[himorishige]

Thank you.
I appreciate that you can fix it.
It seems that this issue is also related to #1518.
This PR will be closed.