Update app.js

@@ -83,14 +83,15 @@ async function handleEvent(event) {
   else if (event.type == 'message'&& event.message.type == 'image') {
     return new Promise(async(resolve,reject)=>{  
       var file;
+      while(file!=undefined)
+    {
       client.getMessageContent(event.message.id)
       .then((stream) => {
         stream.on('data', (chunk) => {
                file=chunk;
         });
       });
-      
-      console.log(file);
+    }     
       var cheerio = require('cheerio');
       var uriBase = 'https://koreacentral.api.cognitive.microsoft.com/vision/v2.1/ocr';
        var options = {