Examine source code of TacoMail

{
  "author": "Oskar2517",
  "description": "Browser extension for TacoMail.de",
  "name": "TacoMail",
  "version": "1.0.1",
  "icons": {
    "16": "icons/16.png",
    "19": "icons/19.png",
    "32": "icons/32.png",
    "38": "icons/38.png",
    "48": "icons/48.png",
    "64": "icons/64.png",
    "96": "icons/96.png",
    "128": "icons/128.png",
    "256": "icons/256.png",
    "512": "icons/512.png"
  },
  "permissions": [
    "storage"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "contact@admin.tacomail.de"
    }
  },
  "action": {
    "default_icon": {
      "16": "icons/16.png",
      "19": "icons/19.png",
      "32": "icons/32.png",
      "38": "icons/38.png"
    },
    "default_popup": "src/entries/popup/index.html"
  },
  "manifest_version": 3
}