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

package.json

@@ -7,7 +7,7 @@
   "typings": "dist_ts/index.d.ts",
   "type": "module",
   "scripts": {
-    "test": "(tstest test/)",
+    "test": "(tstest test/ --verbose --testlog --timeout 20)",
     "build": "(tsbuild --web --allowimplicitany)",
     "buildDocs": "tsdoc"
   },