convert startByte to integer

Condition "!startByte" has never been truthy, because "0" isn't empty string

Author: Deribolot

5-network/09-resume-upload/upload-resume.view/server.js

@@ -10,7 +10,7 @@ let uploads = Object.create(null);
 function onUpload(req, res) {
 
   let fileId = req.headers['x-file-id'];
-  let startByte = req.headers['x-start-byte'];
+  let startByte = parseInt(req.headers['x-start-byte']);
 
   if (!fileId) {
     res.writeHead(400, "No file id");