message: Fix ReadCharFromStdinBlocking
diff: @@ -107,9 +107,10 @@ TEST_SUITE("FindIncludeLine") {
  }
  optional<char> ReadCharFromStdinBlocking() {
  - char c = 0;
  - std::cin.read(&c, 1);
  + char c;
  + if (std::cin.read(&c, 1))
  return c;
  + return nullopt;
  }
  std::unique_ptr<BaseIpcMessage> MessageRegistry::ReadMessageFromStdin(
  