Invalid access to memory - TRemoteFile::GetIsDirectory

I was deleting 1090 empty files from a directory.

WinSCP 5.17.10

Error message:
Invalid access to memory.

Stack trace:
(00CCC25C) TRemoteFile::GetIsDirectory
(00F8A13A) C5296_0
(00F8C1A2) ____ExceptionHandler
(00F88F5C) __ExceptionHandler
(000861AF) ntdll.dll
(00072B31) ntdll.dll.KiUserExceptionDispatcher
(00D96C8C) TTerminal::DeleteFileW
(00D96033) TTerminal::ProcessFiles
(00D971A4) TTerminal::DeleteFiles
(00016154) TCustomScpExplorerForm::DeleteFiles
(000107CD) TCustomScpExplorerForm::ExecuteDeleteFileOperation
(0001088B) TCustomScpExplorerForm::ExecuteFileOperation
(00010A39) TCustomScpExplorerForm::ExecuteFileOperation
(00010ABF) TCustomScpExplorerForm::ExecuteFileOperationCommand
(00043A53) TNonVisualDataModule::ExplorerActionsExecute
(003E939C) System::Actions::TContainedActionList::ExecuteAction

(00CCC25C) TRemoteFile::GetIsDirectory
(00F8A13A) C5296_0
(00F8C1A2) ____ExceptionHandler
(00F88F5C) __ExceptionHandler
(000861AF) ntdll.dll
(00072B31) ntdll.dll.KiUserExceptionDispatcher
(00D96C8C) TTerminal::DeleteFileW
(00D96033) TTerminal::ProcessFiles
(00D971A4) TTerminal::DeleteFiles
(00016154) TCustomScpExplorerForm::DeleteFiles
(000107CD) TCustomScpExplorerForm::ExecuteDeleteFileOperation
(0001088B) TCustomScpExplorerForm::ExecuteFileOperation
(00010A39) TCustomScpExplorerForm::ExecuteFileOperation
(00010ABF) TCustomScpExplorerForm::ExecuteFileOperationCommand
(00043A53) TNonVisualDataModule::ExplorerActionsExecute
(003E939C) System::Actions::TContainedActionList::ExecuteAction

(00F8A7A5) C5296_0
(00F8BD7F) _ReThrowException
(00D96245) TTerminal::ProcessFiles
(00D971A4) TTerminal::DeleteFiles
(00016154) TCustomScpExplorerForm::DeleteFiles
(000107CD) TCustomScpExplorerForm::ExecuteDeleteFileOperation
(0001088B) TCustomScpExplorerForm::ExecuteFileOperation
(00010A39) TCustomScpExplorerForm::ExecuteFileOperation
(00010ABF) TCustomScpExplorerForm::ExecuteFileOperationCommand
(00043A53) TNonVisualDataModule::ExplorerActionsExecute
(003E939C) System::Actions::TContainedActionList::ExecuteAction

(00F8A7A5) C5296_0
(00F8BD7F) _ReThrowException
(000161F3) TCustomScpExplorerForm::DeleteFiles
(000107CD) TCustomScpExplorerForm::ExecuteDeleteFileOperation
(0001088B) TCustomScpExplorerForm::ExecuteFileOperation
(00010A39) TCustomScpExplorerForm::ExecuteFileOperation
(00010ABF) TCustomScpExplorerForm::ExecuteFileOperationCommand
(00043A53) TNonVisualDataModule::ExplorerActionsExecute
(003E939C) System::Actions::TContainedActionList::ExecuteAction

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 5.19.1

Error message:
Error eliminando archivo «stream».

Acceso a memoria no válido

Traza de la pila:
(00CF70F0) TRemoteFile::GetIsDirectory
(00FBC006) C5294_3
(00FBE06E) ____ExceptionHandler
(00FBAE28) __ExceptionHandler
(0008788F) ntdll.dll
(00073EC1) ntdll.dll.KiUserExceptionDispatcher
(00CBD91A) TFTPFileSystem::DeleteFileW
(00DC7B1B) TTerminal::DoDeleteFile
(00DC77A5) TTerminal::DeleteFileW
(00DC6B3F) TTerminal::ProcessFiles
(00DC7CB0) TTerminal::DeleteFiles
(00016590) TCustomScpExplorerForm::DeleteFiles
(00010C0D) TCustomScpExplorerForm::ExecuteDeleteFileOperation
(00010CCB) TCustomScpExplorerForm::ExecuteFileOperation
(00010E79) TCustomScpExplorerForm::ExecuteFileOperation
(00010EFF) TCustomScpExplorerForm::ExecuteFileOperationCommand
(0004681C) TNonVisualDataModule::ExplorerActionsExecute
(0040B3CC) System::Actions::TContainedActionList::ExecuteAction

The problem happens rarely. I cannot reproduce it.