Unify subscription error behavior and update emitted type

[jerelmiller]

Closes #12456
Closes #12422
Closes #12427

Changes the type emitted from subscriptions to a SubscribeResult, which uses error instead of errors. This change also unifies the error behavior between GraphQL errors and network errors so that network errors adhere to the configured errorPolicy. This change means that results are no longer emitted when using errorPolicy: 'ignore' if there is no associated data as well so that we avoid emitting an empty value.

This change also no longer terminates the downstream connection when encountering an error. If the downstream connection closes as a result of the error, a next event will be followed by a complete event instead. This change essentially means that using the error callback is useless and no longer needed. This change allows for additional results to be emitted from the subscription if the subscription remains open after errors are emitted.

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🦋 Changeset detected

Latest commit: b474106

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

This PR includes changesets to release 1 package

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@apollo/client	Major

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Build ID: be694db40e57891bae5e7a0f

[pkg-pr-new]

npm i https://pkg.pr.new/@apollo/client@12476

commit: b474106

[phryneas]

invariant.error will only display in dev and only log, not throw - do we want that behaviour to be dev-only?

[jerelmiller]

I think its ok to leave as dev-only. I'm guessing the original intent here was to let someone know that an error occurred that isn't handled since the error would otherwise get swallowed. I think I'm ok leaving this as a dev-only check since its more of a "warning" that you might want to do something to handle the error.

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[github-actions]

size-limit report 📦

Path	Size
import { ApolloClient, InMemoryCache, HttpLink } from "@apollo/client" (CJS)	41.32 KB (+0.31% 🔺)
import { ApolloClient, InMemoryCache, HttpLink } from "@apollo/client" (production) (CJS)	36.81 KB (+0.09% 🔺)
import { ApolloClient, InMemoryCache, HttpLink } from "@apollo/client"	31.97 KB (+0.32% 🔺)
import { ApolloClient, InMemoryCache, HttpLink } from "@apollo/client" (production)	26.94 KB (+0.19% 🔺)
import { ApolloProvider } from "@apollo/client/react"	5.17 KB (0%)
import { ApolloProvider } from "@apollo/client/react" (production)	960 B (0%)
import { useQuery } from "@apollo/client/react"	6.99 KB (0%)
import { useQuery } from "@apollo/client/react" (production)	2.76 KB (0%)
import { useLazyQuery } from "@apollo/client/react"	6.39 KB (0%)
import { useLazyQuery } from "@apollo/client/react" (production)	2.17 KB (0%)
import { useMutation } from "@apollo/client/react"	6.34 KB (0%)
import { useMutation } from "@apollo/client/react" (production)	2.11 KB (0%)
import { useSubscription } from "@apollo/client/react"	6.74 KB (-1.32% 🔽)
import { useSubscription } from "@apollo/client/react" (production)	2.49 KB (-4.89% 🔽)
import { useSuspenseQuery } from "@apollo/client/react"	8.21 KB (0%)
import { useSuspenseQuery } from "@apollo/client/react" (production)	4 KB (0%)
import { useBackgroundQuery } from "@apollo/client/react"	8.06 KB (0%)
import { useBackgroundQuery } from "@apollo/client/react" (production)	3.83 KB (0%)
import { useLoadableQuery } from "@apollo/client/react"	8.06 KB (0%)
import { useLoadableQuery } from "@apollo/client/react" (production)	3.87 KB (0%)
import { useReadQuery } from "@apollo/client/react"	5.83 KB (0%)
import { useReadQuery } from "@apollo/client/react" (production)	1.61 KB (0%)
import { useFragment } from "@apollo/client/react"	5.89 KB (0%)
import { useFragment } from "@apollo/client/react" (production)	1.66 KB (0%)