message: Fail when no model specified
diff: @@ -1260,6 +1260,12 @@ int main(int argc, char** argv)
  return EXIT_FAILURE;
  }
  + if (rend.filenames.empty())
  + {
  + std::cout << rend.cmd_line_inst().help(argv[0]) << "\n";
  + return EXIT_FAILURE;
  + }
  +
  rend.gl_debug_callback.activate();
  // Load the scene
  