PowerMonitor registered OS-level callbacks (HWND UserData and
WTS/suspend notifications on Windows, shutdown handler and lock-screen
observer on macOS) but never cleaned them up in its destructor. The JS
layer also only held the native object in a closure-local variable,
allowing GC to reclaim it while those registrations still referenced
freed memory.
Retain the native PowerMonitor at module level in power-monitor.ts so
it cannot be garbage-collected. Add DestroyPlatformSpecificMonitors()
to properly tear down OS registrations on destruction: on Windows,
unregister WTS and suspend notifications, clear GWLP_USERDATA, and
destroy the HWND; on macOS, remove the emitter from the global
MacLockMonitor and reset the Browser shutdown handler.
Co-authored-by: trop[bot] <37223003+trop[bot]@users.noreply.github.com>
Co-authored-by: Shelley Vohr <shelley.vohr@gmail.com>
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