message: Fix conhost crashing on `--headless` without `--signal`
  It's not supported, and it shouldn't be.
  But this is the absolutely most minimal way to get the crash to go away.
  Closes
diff: @@ -324,9 +324,16 @@ bool VtIo::IsUsingVt() const
  // first created.
  // - Refer to GH#13066 for details.
  void VtIo::CreatePseudoWindow()
  +{
  + if (_pPtySignalInputThread)
  {
  _pPtySignalInputThread->CreatePseudoWindow();
  }
  + else
  + {
  + ServiceLocator::LocatePseudoWindow();
  + }
  +}
  void VtIo::SetWindowVisibility(bool showOrHide) noexcept
  {
  