Comment 3 for bug 1661295

bug #1661163 is about an incomplete MirDisplayConfig without any cards..

This one is different - the index passed to Get(index) turns out negative:
This is the code causing this.
  // repeated .mir.protobuf.DisplayMode mode = 3;
  for (int i = 0; i < this->mode_size(); i++) {
    ::google::protobuf::internal::WireFormatLite::WriteMessage(
      3, this->mode(i), output);
  }