message: Remove unused variable `ex` in initialize.cc
diff: @@ -496,7 +496,7 @@ struct InitializeHandler : BaseMessageHandler<Ipc_InitializeRequest> {
  JsonReader json_reader{&reader};
  try {
  Reflect(json_reader, *config);
  - } catch (std::invalid_argument& ex) {
  + } catch (std::invalid_argument&) {
  // This will not trigger because parse error is handled in
  // MessageRegistry::Parse in language_server_api.cc
  }
  