I made a mistake
I configured Webpack for an app, not for library and that was the mistake I made.
I changed Webpack’s configuration. SimpleDebugger can be used as
<script> tag in a browser.
What else I changed
I extracted Logger
I refactored ClassNames and every class is written in kebab-case.
var myLogger = new SimpleDebugger.Logger(0); myLogger.add('Testing... Testing...');