search_option3

@@ -71,7 +71,7 @@ function handleEvent(event) {
   else if(event.message.text.substr(0,4) == "!검색 "){
     return new Promise(function(resolve, reject) {
       var text_len = event.message.text;
-      search_api_url += '?query=' + event.message.text.substr(4, text_len - 4) + '&display=1';
+      search_api_url += '?query=' + String(event.message.text.substr(4, text_len - 4)) + '&display=1';
       var search_options = {
         url : search_api_url,
         headers: {'X-Naver-Client-Id': client_id, 'X-Naver-Client-Secret': client_secret}