Examine source code of Smart Tab Closer

{
  "manifest_version": 3,
  "name": "Smart Tab Closer",
  "version": "1.1",
  "description": "Smart Tab Closer Firefox Extension",
  "permissions": [
    "storage",
    "activeTab",
    "scripting"
  ],
  "action": {
    "default_popup": "popup.html"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "smart-tab-closer@example.com",
      "strict_min_version": "140.0",
      "data_collection_permissions": {
        "required": [
          "none"
        ]
      }
    },
    "gecko_android": {
      "strict_min_version": "142.0"
    }
  }
}