Range check error - UnixExtractFileExt

This is my first bug report. So, if there is something I do wrong, please tell me.
I use WinSCP on windows 10 pro 64 bits.
I use an FTP session. And I use Synchronize browsing. I browse from the local side. and then...
And this error dialog keeps showing every time I close the dialog.
Here's the screenshot:


WinSCP 5.11.1

Error message:
Range check error

Stack trace:
(003E9AAB) System::SysFreeMem
(000851CF) ntdll.dll
(00073161) ntdll.dll.KiUserExceptionDispatcher
(006E68D4) UnixExtractFileExt
(006EC1A6) TRemoteFile::GetExtension
(0066BA76) TUnixDirView::GetDisplayInfo
(00417072) Customdirview::TCustomDirView::CNNotify
(0025305D) Vcl::Controls::TControl::WndProc
(00257BA1) Vcl::Controls::TWinControl::WndProc
(0029BACF) Vcl::Comctrls::TCustomListView::WndProc
(00257D07) Vcl::Controls::_17076
(00257BA1) Vcl::Controls::TWinControl::WndProc
(002571E8) Vcl::Controls::TWinControl::MainWndProc
(0037BB94) System::Classes::_18201
(00031B59) USER32.dll
(000240EE) USER32.dll
(00023D45) USER32.dll
(0002DC67) USER32.dll
(0007311B) ntdll.dll.KiUserCallbackDispatcher
(0000F90A) USER32.dll.SendMessageW
(0006BBA6) COMCTL32.DLL
(0006C295) COMCTL32.DLL
(000377A5) COMCTL32.DLL
(00074796) COMCTL32.DLL
(00073897) COMCTL32.DLL
(000740D1) COMCTL32.DLL
(0007402A) COMCTL32.DLL
(000741D4) COMCTL32.DLL
(00072F3B) COMCTL32.DLL
(0006F290) COMCTL32.DLL
(0006D23E) COMCTL32.DLL
(00031B59) USER32.dll
(000240EE) USER32.dll
(00019EB2) USER32.dll.CallWindowProcW
(00257CB2) Vcl::Controls::TWinControl::DefaultHandler
(0025C01B) Vcl::Controls::TWinControl::WMPrintClient
(0025305D) Vcl::Controls::TControl::WndProc
(00257BA1) Vcl::Controls::TWinControl::WndProc
(0029BACF) Vcl::Comctrls::TCustomListView::WndProc
(002585DB) Vcl::Controls%3

The problem happens rarely. I cannot reproduce it.

<Try to describe precise steps that lead to the problem (where do you click, what keys do you press, what do you see, etc.)>
<If relevant, consider attaching a session log file or a screenshot)>

WinSCP 5.13.1

Error message:
メモリのアクセス違反

スタック トレース:
(006F37D0) UnixExtractFileExt
(006F91BA) TRemoteFile::GetExtension
(0067751E) TUnixDirView::GetDisplayInfo
(0041ABEA) Customdirview::TCustomDirView::CNNotify
(00254ED1) Vcl::Controls::TControl::WndProc
(00259A15) Vcl::Controls::TWinControl::WndProc
(0029D943) Vcl::Comctrls::TCustomListView::WndProc
(00259B7B) Vcl::Controls::_17076
(00259A15) Vcl::Controls::TWinControl::WndProc
(0025905C) Vcl::Controls::TWinControl::MainWndProc
(0037ED60) System::Classes::_18201
(000152F7) USER32.dll
(00015D35) USER32.dll
(00015DE3) USER32.dll
(00015E41) USER32.dll
(0000F137) ntdll.dll.KiUserCallbackDispatcher
(000186C0) USER32.dll.SendMessageW
(0002B06D) COMCTL32.DLL
(000263D9) COMCTL32.DLL
(00082013) COMCTL32.DLL
(00027D84) COMCTL32.DLL
(00027E5B) COMCTL32.DLL
(000275F1) COMCTL32.DLL
(00026CA2) COMCTL32.DLL
(00026C26) COMCTL32.DLL
(00026B81) COMCTL32.DLL
(00026CBF) COMCTL32.DLL
(0002EE7B) COMCTL32.DLL
(000152F7) USER32.dll
(00015D35) USER32.dll
(0001FD3A) USER32.dll
(0001FD60) USER32.dll.CallWindowProcW
(00259B26) Vcl::Controls::TWinControl::DefaultHandler
(0025A566) Vcl::Controls::TWinControl::WMPaint
(0029F759) Vcl::Comctrls::TCustomListView::WMPaint
(00259A15) Vcl::Controls::TWinControl::WndProc
(0029D943) Vcl::Comctrls::TCustomListView::WndProc
(

The problem happens rarely. I cannot reproduce it.

<Try to describe precise steps that lead to the problem (where do you click, what keys do you press, what do you see, etc.)>
<If relevant, consider attaching a session log file or a screenshot)>

WinSCP 5.13.1

Error message:
Invalid access to memory.

Stack trace:
(003F13DE) System::UStrAsg
(00062496) ntdll.dll
(0000F13E) ntdll.dll.KiUserExceptionDispatcher
(006F37D0) UnixExtractFileExt
(006F91BA) TRemoteFile::GetExtension
(0067751E) TUnixDirView::GetDisplayInfo
(0041ABEA) Customdirview::TCustomDirView::CNNotify
(00254ED1) Vcl::Controls::TControl::WndProc
(00259A15) Vcl::Controls::TWinControl::WndProc
(0029D943) Vcl::Comctrls::TCustomListView::WndProc
(00259B7B) Vcl::Controls::_17076
(00259A15) Vcl::Controls::TWinControl::WndProc
(0025905C) Vcl::Controls::TWinControl::MainWndProc
(0037ED60) System::Classes::_18201
(000152F7) USER32.dll
(00015D35) USER32.dll
(00015DE3) USER32.dll
(00015E41) USER32.dll
(0000F117) ntdll.dll.KiUserCallbackDispatcher
(000186C0) USER32.dll.SendMessageW
(0002B06D) COMCTL32.DLL
(000263D9) COMCTL32.DLL
(00082013) COMCTL32.DLL
(00027D84) COMCTL32.DLL
(00027E5B) COMCTL32.DLL
(000275F1) COMCTL32.DLL
(00026CA2) COMCTL32.DLL
(00026C26) COMCTL32.DLL
(00026B81) COMCTL32.DLL
(00026CBF) COMCTL32.DLL
(0002EE7B) COMCTL32.DLL
(000152F7) USER32.dll
(00015D35) USER32.dll
(0001FD3A) USER32.dll
(0001FD60) USER32.dll.CallWindowProcW
(00259B26) Vcl::Controls::TWinControl::DefaultHandler
(0025DE8F) Vcl::Controls::TWinControl::WMPrintClient
(00254ED1) Vcl::Controls::TControl::WndProc
(00259A15) Vcl::Controls::TWinControl::WndProc
(0029D943) Vcl::Comctrls::TCustomListView::WndProc%0

The problem happens rarely. I cannot reproduce it.