tsconfig.json

{
  "compilerOptions": {
    "module": "commonjs",
    "esModuleInterop": true,
    "target": "es6",
    "moduleResolution": "node16",
    // This is required for closures to be properly serialized.
    // Without this one gets errors like "ReferenceError: [val] is not defined"
    "plugins": [
      {
        "transform": "ts-closure-transform",
        "import": "beforeTransform"
      },
      {
        "transform": "ts-closure-transform",
        "import": "afterTransform",
        "after": true
      }
    ],
    "sourceMap": true,
    "outDir": "dist"
  },
  "lib": ["es2015"]
}