[4.1.2 Backport] CBG-5522: Implement ScanResultIterator.Err() in gocb range scan wrapper

[bbrks]

CBG-5522

Clean cherry pick of #8403 to 4.1.2

Second of a 6-PR stack backporting CBG-5547, stacked on the CBG-5460 backport. This PR is a prerequisite discovered while cherry-picking: the sg-bucket version the CBG-5547 layers need adds Err() to the ScanResultIterator interface, and this is the commit that implements it in the gocb range scan wrapper. Without it the tree does not compile.

Dependency upgrade — what is actually changing

github.com/couchbase/sg-bucket d9dd0c058146 → fc995d3ac4be (compare):

Commit	Change	Risk
#148	CBG-5522: Add Err() to ScanResultIterator interface for range scans	Interface addition. Breaks the build until the implementations catch up, which is what this PR's Go changes do

github.com/couchbaselabs/rosmar 3e0b3eaeb1b1 → 11d9680fd14d (compare):

Commit	Change	Risk
#82	CBG-5522: Implement ScanResultIterator.Err()	Matches sg-bucket #148
#69	CBG-4232 implement hierarchical subdoc path support	The one functional rosmar change in this stack. Affects rosmar's subdoc handling, so it changes unit-test behaviour under the rosmar backing store; it cannot affect a Couchbase Server deployment

Verified on CE with the rosmar backing store: go build ./..., go vet ./..., go test ./base/, golangci-lint run --config=.golangci-strict.yml --new-from-rev=origin/release/4.1.2 and golangci-lint fmt --config=.golangci-strict.yml --diff. The range scan tests only exercise the gocb wrapper against a real Couchbase Server, and integration tests were not run — so the Err() implementation itself is covered by compile and lint here, not by an executed test.

No [4.1.2 Backport] ticket exists for this change, so the title carries the upstream ticket key.

🤖 Opened with the sync-gateway-backport skill in Claude Code

[Copilot]

Pull request overview

Backports CBG-5522 to the 4.1.2 branch by updating sg-bucket/rosmar dependencies and implementing the newly-required ScanResultIterator.Err() method for the gocb range scan wrapper so the tree compiles and range scan behavior can be inspected consistently.

Changes:

• Bump github.com/couchbase/sg-bucket and github.com/couchbaselabs/rosmar to versions that add/implement ScanResultIterator.Err().
• Implement Err() for gocbScanResultIterator and adjust Close() behavior to preserve/translate stream errors consistently.
• Extend range scan tests to assert Err() behavior, including post-Close() cancellation semantics.

Reviewed changes

Copilot reviewed 3 out of 4 changed files in this pull request and generated 1 comment.

File	Description
go.mod	Updates sg-bucket and rosmar module versions required by the new iterator interface.
go.sum	Updates checksums for the upgraded sg-bucket and rosmar versions.
base/collection_rangescan.go	Adds gocbScanResultIterator.Err() and refines Close() error/cancellation handling.
base/collection_rangescan_test.go	Adds Err() assertions and a subtest validating cancellation visibility after Close().