If you parse a serialized protobuf byte array without having a .proto file, you have no way to dustinguish a byte string field from a nested message field. Thus you have no way to know how deep your parser should go.
[0]: https://github.com/trymoose/handwriting2svg/blob/0eb56cf4582...
[1]: https://github.com/ReagentX/imessage-exporter/blob/beeb853b2...
[2]: https://github.com/ReagentX/imessage-exporter/blob/beeb853b2...