List index out of bounds (-1) - TTerminalManager::FreeActiveTerminal

<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 6.1.1

Error message:
List index out of bounds (-1)

Stack trace:
(01002F8A) __DynamicCastVCLptr
(0003EC2E) ntdll.dll.ZwWow64CallFunction64
(0003F3AA) ntdll.dll.KiUserExceptionDispatcher
(000BD1EF) TTerminalManager::FreeActiveTerminal
(00C90612) TThemePageControl::Dispatch
(003F62DD) Vcl::Controls::TWinControl::WndProc
(003F5924) Vcl::Controls::TWinControl::MainWndProc
(00214D98) System::Classes::_18201
(00007FFF) USER32.DLL.CallNextHookEx
(0000825C) USER32.DLL
(00010350) USER32.DLL.CallWindowProcW
(004AFCAF) Dragdrop::TDragDrop::WndMethod
(00214D98) System::Classes::_18201
(00007FFF) USER32.DLL.CallNextHookEx
(0000825C) USER32.DLL
(000097FA) USER32.DLL
(0000986B) USER32.DLL.DispatchMessageW

(001F7831) System::Classes::TList::Get
(001F7831) System::Classes::TList::Get
(000BD1EF) TTerminalManager::FreeActiveTerminal
(00C90612) TThemePageControl::Dispatch
(003F62DD) Vcl::Controls::TWinControl::WndProc
(003F5924) Vcl::Controls::TWinControl::MainWndProc
(00214D98) System::Classes::_18201
(00007FFF) USER32.DLL.CallNextHookEx
(0000825C) USER32.DLL
(00010350) USER32.DLL.CallWindowProcW
(004AFCAF) Dragdrop::TDragDrop::WndMethod
(00214D98) System::Classes::_18201
(00007FFF) USER32.DLL.CallNextHookEx
(0000825C) USER32.DLL
(000097FA) USER32.DLL
(0000986B) USER32.DLL.DispatchMessageW

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 6.1.2

Error message:
List index out of bounds (-1)

Stapelverfolgung:
(01003866) __DynamicCastVCLptr
(000981DF) ntdll.dll
(00077D51) ntdll.dll.KiUserExceptionDispatcher
(000BDAA3) TTerminalManager::FreeActiveTerminal
(00C90ED2) TThemePageControl::Dispatch
(003F6B91) Vcl::Controls::TWinControl::WndProc
(003F61D8) Vcl::Controls::TWinControl::MainWndProc
(0021564C) System::Classes::_18201
(00031BC1) USER32.dll
(000229B1) USER32.dll
(00022322) USER32.dll.CallWindowProcW
(004B0563) Dragdrop::TDragDrop::WndMethod
(0021564C) System::Classes::_18201
(00031BC1) USER32.dll
(000229B1) USER32.dll
(00021270) USER32.dll
(00020DBB) USER32.dll.DispatchMessageW

(001F80E5) System::Classes::TList::Get
(001F80E5) System::Classes::TList::Get
(000BDAA3) TTerminalManager::FreeActiveTerminal
(00C90ED2) TThemePageControl::Dispatch
(003F6B91) Vcl::Controls::TWinControl::WndProc
(003F61D8) Vcl::Controls::TWinControl::MainWndProc
(0021564C) System::Classes::_18201
(00031BC1) USER32.dll
(000229B1) USER32.dll
(00022322) USER32.dll.CallWindowProcW
(004B0563) Dragdrop::TDragDrop::WndMethod
(0021564C) System::Classes::_18201
(00031BC1) USER32.dll
(000229B1) USER32.dll
(00021270) USER32.dll
(00020DBB) USER32.dll.DispatchMessageW

The problem happens rarely. I cannot reproduce it.