Fix handling of warnings on DML batches

[ggilder]

Related issue: #1636

Description

This is a follow-up to #1633 — this was actually an incomplete fix for the data loss issue described there, because any DML events that would cause data loss that happened in the middle of a batch could be masked by success of the final statement in the batch. This code change now runs SHOW WARNINGS after each statement in a batch so that we collect all warnings.

• contributed code is using same conventions as original code
• script/cibuild returns with no formatting errors, build errors or unit test errors.

[Copilot]

Pull request overview

Improves --panic-on-warnings safety during binlog replay by ensuring warnings emitted by any statement inside a batched DML multi-statement are detected (not just the last statement), addressing the masking/data-loss scenario from #1636 / follow-up to #1633.

Changes:

• Add executeBatchWithWarningChecking() to interleave SHOW WARNINGS after each DML in a batch when PanicOnWarnings is enabled.
• Update ApplyDMLEventQueries() to use the new warning-checking execution path only for PanicOnWarnings (keep existing fast path otherwise).
• Add a new unit test and a new local integration test case to validate “warning in the middle of a batch” behavior.

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 4 comments.

Show a summary per file

File	Description
localtests/panic-on-warnings-batch-middle/extra_args	Adds localtest arguments enabling --panic-on-warnings with a unique index alter.
localtests/panic-on-warnings-batch-middle/expect_failure	Asserts failure output contains warning-detection text.
localtests/panic-on-warnings-batch-middle/create.sql	Sets up event-driven DML to reproduce a batched replay scenario.
go/logic/applier_test.go	Adds unit test asserting mid-batch warning causes rollback of entire batch.
go/logic/applier.go	Implements per-statement warning detection for batched DML execution under PanicOnWarnings.

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

You can also share your feedback on Copilot code review. Take the survey.

[ggilder]

@meiji163 important correction to earlier data loss fix — lmk if you have questions