Fix return types for pagination handlers

[SeppahBaws]

This fixes a subtle bug that crept in with #1352, where the return types for loadNextPage and loadPreviousPage became Promise<QueryResult<_Data, _Input> | undefined> instead of the Promise<QueryResult<_Data, _Input>> as defined by the CursorHandlers type.

To help everyone out, please make sure your PR does the following:

• Update the first line to point to the ticket that this PR fixes
• Add a message that clearly describes the fix
• If applicable, add a test that would fail without this fix
• Make sure the unit and integration tests pass locally with pnpm run tests and cd integration && pnpm run tests
• Includes a changeset if your fix affects the user with pnpm changeset

[changeset-bot]

🦋 Changeset detected

Latest commit: 08cdc95

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

This PR includes changesets to release 9 packages

Name	Type
houdini-svelte	Patch
houdini-plugin-svelte-global-stores	Patch
houdini-adapter-auto	Patch
houdini-adapter-cloudflare	Patch
houdini-adapter-node	Patch
houdini-adapter-static	Patch
houdini-react	Patch
houdini	Patch
create-houdini	Patch

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