Tweak withClientState signature to work around typescript bug

[Phoenixmatrix]

Resolves #158

This is a non-ideal fix for #158, related on a TypeScript issue that should be fixed, but apparently is not (microsoft/TypeScript/issues/8681). The relevent comment in that issue is this one

The typescript code in apollo-link-state is perfectly fine and would work as is, but the generated type definition, after compilation is:

export declare const withClientState: ({resolvers, defaults, cache}?: ClientStateConfig)

With strict null enabled, you'll get an error message because it is impossible to destructure the fields when the object is nullable (because of the ? after the curly brace). At runtime this isn't an issue since withClientState's argument has a default value.

This PR changes the signature to "trick" the compiler a little: by doing the destructuring inside of the function, the generated .d.ts will not have destructuring, and the problem goes away.

It's not great to have to do this, but typescript with strict null is sooooooooo good, it's hard to give up :)

I'll follow up by opening a new issue on the typescript repo, but history has shown issues like that can take a long time to get fixed there.

[apollo-cla]

@Phoenixmatrix: Thank you for submitting a pull request! Before we can merge it, you'll need to sign the Meteor Contributor Agreement here: https://contribute.meteor.com/

[Phoenixmatrix]

(I want to say the current build failure is because the npm registry is currently sad. It will probably work later.)

[fbartho]

This looks good to me; does anybody know how to kick travis so it tries the build again? NPM claims the issues are resolved.

[Phoenixmatrix]

Someone with write access should be able to just kick it off? Alternatively I can close and reopen the PR.

[codecov-io]

Codecov Report

Merging #165 into master will increase coverage by 0.06%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master     #165      +/-   ##
==========================================
+ Coverage   95.58%   95.65%   +0.06%     
==========================================
  Files           2        2              
  Lines          68       69       +1     
  Branches       18       18              
==========================================
+ Hits           65       66       +1     
  Misses          3        3

Impacted Files	Coverage Δ
packages/apollo-link-state/src/index.ts	96.42% <100%> (+0.06%)	⬆️

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[fbartho]

I had the power to kick!

Looks good to me!

[peggyrayzis]

Thanks for making this fix!

[wearethefoos]

Nice! @peggyrayzis @fbartho any chance this will be released soon? 🙏 😄