tsconfig.json

{
  "compilerOptions": {
    "outDir": "./dist/",
    "sourceMap": true,
    "moduleResolution": "node",
    "module": "CommonJS",
    "target": "ES2015",
    "declaration": false,
    "downlevelIteration": true,
    "jsx": "react",
    "allowJs": true,

    "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. */

    "noImplicitReturns": true,                /* Report error when not all code paths in function return a value. */
    "noFallthroughCasesInSwitch": true        /* Report errors for fallthrough cases in switch statement. */
  }
}