在Delphi 7中将TMemoryStream转换为WideString

Question

当我在 Delphi 7 中使用此代码和函数时，将显示错误消息：

此代码将MemoryStream内容转换为WideString

function ReadWideString(stream: TStream): WideString;
var
  nChars: LongInt;
begin
  stream.Position := 0;
  stream.ReadBuffer(nChars, SizeOf(nChars));
  SetLength(Result, nChars);
  if nChars > 0 then
    stream.ReadBuffer(Result[1], nChars * SizeOf(Result[1]));
end;


procedure TForm1.Button2Click(Sender: TObject);
var
  mem: TMemoryStream;
begin
  mem := TMemoryStream.Create;
  mem.LoadFromFile('C:\Users\User1\Desktop\wide.txt');
  Memo1.Lines.Add(ReadWideString(mem));
end;

非常感谢任何帮助。