fix(bindings): Fix handlers for subscriptions receiving null

[kitten]

Summary

Note

Reported on Discord

The subscription handlers infer their new value argument type as T of OperationResult<T>. This means that data: null cases are uncovered and the handler may accidentally receive null values when the types specify that this isn't possible.

This may happen when a trailing value of a subscription contains a fatal error rather than a result value.

In this case it should be safe to ignore the value, since the subscription will either be restarted by the subscription client (or a retryExchange), or will terminate.

Set of changes

• Handle null values before passing result.data to subscription handlers

[changeset-bot]

🦋 Changeset detected

Latest commit: e7add61

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

This PR includes changesets to release 4 packages

Name	Type
@urql/preact	Patch
@urql/svelte	Patch
urql	Patch
@urql/vue	Patch

Not sure what this means? Click here to learn what changesets are.

Click here if you're a maintainer who wants to add another changeset to this PR