refactor: replace magic strings with os abstraction

Author: digitalsadhu

lib/reader.js

@@ -1,6 +1,7 @@
 'use strict';
 
 const assert = require('assert');
+const { EOL } = require('os');
 
 module.exports = async function reader(feeds = []) {
     assert(
@@ -26,5 +27,5 @@ module.exports = async function reader(feeds = []) {
     // backwards compatible refactor to `.source` from `.content`
     return Array.from(feedMap.values())
         .map(feed => (feed.source || feed.content).trim())
-        .join('\n\n');
+        .join(EOL + EOL);
 };