chore: refactor main code base into smaller parts

lib/debug.js

@@ -1,12 +1,15 @@
 'use strict'
 
-const index = require('../')
+var index
+function lazyIndex () {
+  return index || require('../')
+}
 
 /**
  * @description Print a debug statement if in debug mode
  */
 function debug () {
-  if (index.debugMode) {
+  if (lazyIndex().debugMode) {
     console.error.apply(null, arguments)
   }
 }