First chance exception at $00000000003D1910. Exception class $C0000005 with message 'c0000005 ACCESS_VIOLATION'.

Data.DB.TDataSet.DataEvent(deFieldChange,2058754320)
MemTableEh.TCustomMemTableEh.DataEvent(deFieldChange,2058754320)
MemTableEh.TCustomMemTableEh.SetFieldData($26C7AB61910, ...
Data.DB.TField.SetData((49...
Data.DB.TStringField.SetAsAnsiString(???)
Data.DB.TStringField.SetAsString('1')

program TestMt;

{$APPTYPE CONSOLE}

{$R *.res}

uses
  System.SysUtils, DB, MemTableEh;

begin
  try
    var mt := TMemTableEh.Create(nil);
    try
      mt.FieldDefs.Add('name', ftString, 100, false);
      mt.CreateDataSet();

      //mt.AppendRecord(['hello!']);

      mt.Append();
      mt.Edit();
      mt.FieldByName('name').AsString := '1';
      mt.Post();

      mt.ApplyUpdates(0); // just another code line
    finally
      mt.Free();
    end;
  except
    on E: Exception do
      Writeln(E.ClassName, ': ', E.Message);
  end;
end.