fix(qenv): Handle falsy environment values correctly, improve env source resolution, add tests and update test script

ts/00_commitinfo_data.ts

@@ -3,6 +3,6 @@
  */
 export const commitinfo = {
   name: '@push.rocks/qenv',
-  version: '6.1.2',
+  version: '6.1.3',
   description: 'A module for easily handling environment variables in Node.js projects with support for .yml and .json configuration.'
 }