ethers.js/tsconfig.json

{
  "compilerOptions": {

    "declaration": true,
    "esModuleInterop": true,
    "lib": [ "es2015", "es5", "dom" ],
    "module": "commonjs",
    "outDir": "./src/",
    "target": "es5",
    "moduleResolution": "node",
    "resolveJsonModule": true,

    "preserveSymlinks": true,

    "preserveWatchOutput": true,
    "pretty": false,
    "forceConsistentCasingInFileNames": true,
    "removeComments": false,

    "noFallthroughCasesInSwitch": true,
    "noImplicitReturns": true,
    "noUnusedLocals": true
  },
  "include": [
    "src.ts/*.ts",
    "src.ts/**/*.ts"
  ]
}