tsconfig.json

{
  "compilerOptions": {
    /* Basic Options */
    // Node 8 LTS is no longer supported, so we should be able to safely target es2018 here:
    // https://node.green/#ES2018
    "target": "ES2017",                          /* Specify ECMAScript target version: 'ES3' (default), 'ES5', 'ES2015', 'ES2016', 'ES2017','ES2018' or 'ESNEXT'. */
    "module": "commonjs",                     /* Specify module code generation: 'none', 'commonjs', 'amd', 'system', 'umd', 'es2015', or 'ESNext'. */
    "lib": ["esnext"],                             /* Specify library files to be included in the compilation. */
    "declaration": true,                   /* Generates corresponding '.d.ts' file. */
    "sourceMap": true,                     /* Generates corresponding '.map' file. */
    "outDir": "./dist",                        /* Redirect output structure to the directory. */
    "strict": true,                           /* Enable all strict type-checking options. */
    "moduleResolution": "node",            /* Specify module resolution strategy: 'node' (Node.js) or 'classic' (TypeScript pre-1.6). */
    "allowSyntheticDefaultImports": true,  /* Allow default imports from modules with no default export. This does not affect code emit, just typechecking. */
    "stripInternal": true,
    "exactOptionalPropertyTypes": true
  }
}