Fix/threading and error handling

[gmacmaster]

No description provided.

[greptile-apps]

Greptile Summary

This PR makes two targeted fixes: removes a redundant double-allocation in the wicBitmapSourceFromStream error-handling path in WindowsImageManager.cpp, and promotes m_usingRendering in Timing.h from a plain bool to std::atomic<bool> (adding the required <atomic> include) to prevent a data race when the field is read/written from multiple threads.

Confidence Score: 5/5

Safe to merge — both changes are small, correct, and targeted fixes with no regressions.

No P0 or P1 findings. The duplicate make_shared removal is strictly correct, and the atomic promotion resolves a real data race. No behavioural regressions are introduced.

No files require special attention.

Important Files Changed

Filename	Overview
vnext/Microsoft.ReactNative/Fabric/WindowsImageManager.cpp	Removes a redundant second std::make_shared() call in the catch block — the first allocation was immediately overwritten, so deleting the duplicate is correct and safe.
vnext/Microsoft.ReactNative/Modules/Timing.h	Adds #include and changes m_usingRendering from bool to std::atomic to fix a threading data race; m_usePostForRendering remains a plain bool which may warrant similar treatment depending on its access pattern.

Sequence Diagram

sequenceDiagram
    participant BG as Background Thread
    participant UI as UI Thread
    participant T as Timing struct

    Note over BG,T: Before fix: plain bool, data race
    BG->>T: read m_usingRendering
    UI->>T: write m_usingRendering
    Note over BG,T: UB: concurrent read and write

    Note over BG,T: After fix: atomic bool, race free
    BG->>T: load m_usingRendering (atomic)
    UI->>T: store m_usingRendering (atomic)
    Note over BG,T: Safe: sequential consistency guaranteed

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