When sentence file not loaded, sentence has one empty token

wcclparser/main.cpp

@@ -210,6 +210,7 @@ int main(int argc, char** argv)
 		boost::shared_ptr<Corpus2::Sentence> sentence;
 		if (sentence_load.empty()) {
 			sentence.reset(new Corpus2::Sentence);
+			sentence->append(new Corpus2::Token("", PwrNlp::Whitespace::ManySpaces));
 		} else {
 			std::ifstream ifs(sentence_load.c_str());
 			if (ifs.good()) {