message: dnn/samples: handle not set env vars gracefully
diff: @@ -58,10 +58,12 @@ std::string findFile(const std::string& filename)
  if (filename.empty() || utils::fs::exists(filename))
  return filename;
  - std::string extraPaths[] = {getenv("OPENCV_DNN_TEST_DATA_PATH"),
  + const char* extraPaths[] = {getenv("OPENCV_DNN_TEST_DATA_PATH"),
  getenv("OPENCV_TEST_DATA_PATH")};
  for (int i = 0; i < 2; ++i)
  {
  + if (extraPaths[i] == NULL)
  + continue;
  std::string absPath = utils::fs::join(extraPaths[i], utils::fs::join("dnn", filename));
  if (utils::fs::exists(absPath))
  return absPath;
  