chore: Output more information about CORS-origin.

app/server/src/index.js

@@ -23,7 +23,7 @@ const corsOptions = {
     if(!origin) return callback(null, true);
     if(whitelist.indexOf(origin) === -1){
       var message = "The CORS policy for this origin doesn't " +
-                "allow access from the particular origin.";
+                `allow access from the particular origin. (Origin: ${origin})`;
       return callback(new Error(message), false);
     }
     return callback(null, true);