style: add debug trace on some file

src/concurrency-implementation.js

@@ -11,6 +11,7 @@ class CustomConcurrency extends Browser {
 
     async workerInstance() {
         const options = this.options.perBrowserOptions.shift();
+        debug('Launch puppeteer instance with options=%o', options);
         let chrome = await this.puppeteer.launch(options);
         let page;
         let context;

src/modules/se_scraper.js

@@ -10,6 +10,7 @@ const debug = require('debug')('se-scraper:Scraper');
 
 module.exports = class Scraper {
     constructor(options = {}) {
+        debug('constructor');
         const {
             config = {},
             context = {},