tsconfig.json

{
    "compilerOptions": {
      "target": "es5",
      "lib": ["es2015", "es2015.promise","dom", "es2017.string"],
      "module": "commonjs",
      "declaration": true,
      "outDir": "./dist",
      "typeRoots": ["./node_modules/@types"],
      "types": ["node"],
      "sourceMap": true,
      "strictPropertyInitialization": false,
  
      /* Strict Type-Checking Options */
      // "strict": true /* Enable all strict type-checking options. */
      // "noImplicitAny": true /* Raise error on expressions and declarations with an implied 'any' type. */,
      "strictNullChecks": true /* Enable strict null checks. */,
      "strictFunctionTypes": true /* Enable strict checking of function types. */,
      "strictBindCallApply": true /* Enable strict 'bind', 'call', and 'apply' methods on functions. */,
      "strictPropertyInitialization": true /* Enable strict checking of property initialization in classes. */,
      "noImplicitThis": true /* Raise error on 'this' expressions with an implied 'any' type. */,
      "alwaysStrict": true /* Parse in strict mode and emit "use strict" for each source file. */,
  
      /* Additional Checks */
      "noUnusedLocals": true /* Report errors on unused locals. */,
      // "noUnusedParameters": true /* Report errors on unused parameters. */,
      "noImplicitReturns": true /* Report error when not all code paths in function return a value. */,
      "noFallthroughCasesInSwitch": true /* Report errors for fallthrough cases in switch statement. */
    },
    "include": ["src/**/*.ts"]
  }