fix: avoid null write during skip deserialize

[LHT129]

Summary

• avoid calling Write(nullptr, size, offset) in the SkipDeserialize deserialize path
• update the skipped IO size directly after seeking past the serialized payload
• add regression coverage that verifies skip-deserialize does not invoke WriteImpl with null data

Fixes: #2402

Testing

• make fmt
• Not run: build/tests, per maintainer instruction to skip build and tests for this task after the initial test attempt was blocked during dependency configuration by fmt download failure.

[mergify]

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[gemini-code-assist]

Code Review

This pull request modifies BasicIO::Deserialize to update this->size_ directly using std::max instead of calling this->Write(nullptr, size, offset) when SkipDeserialize is enabled, preventing unnecessary null writes. It also adds a unit test to verify this behavior. The reviewer suggests simplifying the size calculation by removing the redundant offset variable, which is always zero in this branch.

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[Copilot]

Pull request overview

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This PR fixes the skip-deserialize path to avoid invoking writes with null buffers during deserialization, and adds a regression test to ensure WriteImpl is not called in that mode.

Changes:

• Remove the Write(nullptr, ...) call in BasicIO::Deserialize when SkipDeserialize is enabled, and update size_ directly.
• Add a regression test IO implementation that fails if WriteImpl is ever called with null data.
• Add a new unit test validating cursor/size behavior in skip-deserialize mode.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 3 comments.

File	Description
src/io/reader_io_test.cpp	Adds a regression test and a test IO type to ensure skip-deserialize does not call WriteImpl with null data.
src/io/basic_io.h	Updates skip-deserialize deserialization to skip the payload and update size_ without calling Write(nullptr, ...).

[Copilot]

Pull request overview

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

[vsag-bot]

/label S-ready-to-merge
/waiting-on maintainer
/request-review @jiaweizone
/request-review @inabao

[wxyucs]

lgtm

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