Fix bug when blur command received on node without XamlRoot #12051
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We are seeing crashes on quit when the blur command is called roughly around the same time that the React instance is being shut down. It's likely because the result of tryGetXamlRoot is null. This change falls back on the GetFocusedElement() overload without any parameters if the XamlRoot is null, as supplying a null parameter will result in a NPE.
jonthysell
approved these changes
Aug 28, 2023
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Description
Type of Change
Erase all that don't apply.
Why
We are seeing crashes on quit when the blur command is called roughly around the same time that the React instance is being shut down. It's likely because the result of tryGetXamlRoot is null.
What
This change falls back on the GetFocusedElement() overload without any parameters if the XamlRoot is null, as supplying a null parameter will result in a NPE.
Testing
It's a tricky race condition to repro, but I did validate that passing a null XamlRoot value to
FocusManager::GetFocusedElement(XamlRoot)will throw an exception.Changelog
Should this change be included in the release notes: yes
Fix for NPE when blur command is received while React instance is shutting down.
Microsoft Reviewers: Open in CodeFlow