message: gltfpack: Improve error message for referenced buffers
  When we have loaded the original file, some error codes should be
  translated slightly differently to convey the nuance, e.g. "file not
  found" suggests that the original file can't be loaded, whereas
  "resource" highlights the fact that it's a dependent file.
diff: @@ -177,12 +177,12 @@ struct BufferView
  size_t bytes;
  };
  -const char* getError(cgltf_result result)
  +const char* getError(cgltf_result result, cgltf_data* data)
  {
  switch (result)
  {
  case cgltf_result_file_not_found:
  - return "file not found";
  + return data ? "resource not found" : "file not found";
  case cgltf_result_io_error:
  return "I/O error";
  @@ -200,9 +200,11 @@ const char* getError(cgltf_result result)
  return "legacy GLTF";
  case cgltf_result_data_too_short:
  - case cgltf_result_unknown_format:
  return "not a GLTF file";
  + case cgltf_result_unknown_format:
  + return data ? "unknown resource format" : "not a GLTF file";
  +
  default:
  return "unknown error";
  }
  @@ -4130,7 +4132,7 @@ int gltfpack(const char* input, const char* output, const Settings& settings)
  const char* error = NULL;
  if (result != cgltf_result_success)
  - error = getError(result);
  + error = getError(result, data);
  else if (requiresExtension(data, "KHR_draco_mesh_compression"))
  error = "file requires Draco mesh compression support";
  else if (requiresExtension(data, "MESHOPT_compression"))
  