fix(graphcache): Mutable links on InMemoryData store

[kitten]

See related PR: #3503

Summary

When cache.resolve returns a list of entity links, i.e. an array link, a user may be tempted to mutate this list before writing it back to the store.

This can have unforeseen consequences if:

• cache.link then doesn't write to the same layer
• cache.link isn't called at all
• the array is completely changed and then read back in an unrelated operation

This is because, unlike cache.link, cache.resolve doesn't make a copy of links before returning them. This means that mutating a link array leads to direct modifications to the internal caching layer.

Set of changes

• Call ensureLink before returning the links via cache.resolve to copy them

[changeset-bot]

🦋 Changeset detected

Latest commit: 38d3194

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

This PR includes changesets to release 1 package

Name	Type
@urql/exchange-graphcache	Patch

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