message: add a missing impl
diff: @@ -616,4 +616,9 @@ impl Artifact for NativeArtifact {
  fn preinstantiate(&self) -> Result<(), InstantiationError> {
  Ok(())
  }
  +
  + /// Serialize a NativeArtifact
  + fn serialize(&self) -> Result<Vec<u8>, SerializeError> {
  + Ok(std::fs::read(&self.sharedobject_path)?)
  + }
  }
  