EngineMupdf::GetFzPageInfo crash entering pagesAccess critical section

[kjk]

ntdll.dll!RtlEnterCriticalSection+0x42 sumatrapdf.exe!EngineMupdf::GetFzPageInfo+0x3b C:\Users\kjk\src\sumatrapdf\src\EngineMupdf.cpp+2561 sumatrapdf.exe!EngineMupdfCreateAnnotation+0x50 C:\Users\kjk\src\sumatrapdf\src\EditAnnotations.cpp+1461 sumatrapdf.exe!OnWindowContextMenu+0x743 C:\Users\kjk\src\sumatrapdf\src\Menu.cpp+1922 sumatrapdf.exe!OnMouseRightButtonUp+0xfc C:\Users\kjk\src\sumatrapdf\src\Canvas.cpp+692 sumatrapdf.exe!WndProcCanvasFixedPageUI+0x2ef C:\Users\kjk\src\sumatrapdf\src\Canvas.cpp+1413 sumatrapdf.exe!WndProcCanvas+0xa7 C:\Users\kjk\src\sumatrapdf\src\Canvas.cpp+1715

No other thread of significance.

StartMonitoringDirForChangesAPC() C:\Users\YuJian\AppData\Local\SumatraPDF
LoadDocument: 7.77 ms, 679 pages for 'F:\idm download\心理学与生活 第19版.pdf (心理学与生活 第19版.pdf) (z-lib.org).pdf'
DisplayModel::BuildPagesInfo started
DisplayModel::BuildPagesInfo took 0.01 ms
StartMonitoringDirForChangesAPC() F:\idm download
Saved annotations to 'F:\idm download\心理学与生活 第19版.pdf (心理学与生活 第19版.pdf) (z-lib.org).pdf' in  3815.18 ms
DisplayModel::BuildPagesInfo started
DisplayModel::BuildPagesInfo took 0.01 ms

Theory: reloading a doc on a slow (e.g. network) drive triggered by saving an annotation.

This somehow caused EngineMupdf to be destroyed which destroyed critical section but we still reference this Figure out how this happened. Add logging to ~EngineMupdf

No luck reprodcing so far (annotating a doc on network drive, saving annotations with Ctrl-Shift-S etc.).