fix(firestore): correct misleading cross-database reference log

[llamington]

Fixes the log in AbstractUserDataWriter.convertDocumentKey so it stops naming the reference's target as though that document contained the reference.

Filed first as #10249, which has the details and a repro.

Before:

Document targets/the-target contains a document reference within a different database (demo-project-b/(default)) which is not supported. ...

After:

A document reference to targets/the-target refers to a different database (demo-project-b/(default)), which is not supported. ...

targets/the-target is what the reference points at. The document that actually holds it (containers/the-container in the repro) was never named, because both the database id and the document key are parsed from the reference value itself.

Testing

Nothing asserts this string anywhere in the repo, and only log copy changes, so no behaviour is affected.

I haven't added a test. Asserting on log wording would make any future rewording brittle, and the assertion actually worth having (that the log names the containing document) isn't satisfied by this change. Happy to add one if you'd prefer.

API changes

None. AbstractUserDataWriter is @internal and doesn't appear in common/api-review/firestore.api.md. No signatures change, and firestore-compat picks this up automatically since it calls convertDocumentKey rather than reimplementing it.

Naming the containing document would be the better fix, but it looks disproportionate for a diagnostic string: the key would have to be threaded through convertValue → convertObject → convertObjectMap/convertArray → convertReference (protected abstract, so every subclass changes) → convertDocumentKey, across both firestore and firestore-compat. It would also have to be optional, since aggregate_types.ts and pipeline-result.ts hold a writer for results that aren't document fields. Glad to attempt that instead if you'd rather.

Changeset included, patch bump on @firebase/firestore.

[changeset-bot]

🦋 Changeset detected

Latest commit: 56fffeb

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

This PR includes changesets to release 3 packages

Name	Type
@firebase/firestore	Patch
firebase	Patch
@firebase/firestore-compat	Patch

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[gemini-code-assist]

Code Review

This pull request corrects an error log message in @firebase/firestore when a document reference points to a different database. The log message was previously misleading, stating that the document itself contained the reference, whereas it is actually the target of the reference. A corresponding changeset has also been added. There are no review comments, so I have no feedback to provide.