feat(#251)!: treat empty strings as missing environment variables - #252

Node.js 20 is deprecated. The following actions target Node.js 20 but are being forced to run on Node.js 24: actions/checkout@34e114876b0b11c390a56381ad16ebd13914f8d5, github/codeql-action/analyze@dd903d2e4f5405488e5ef1422510ee31c8b32357, github/codeql-action/init@dd903d2e4f5405488e5ef1422510ee31c8b32357. For more information see: https://github.blog/changelog/2025-09-19-deprecation-of-node-20-on-github-actions-runners/