tsconfig.json

{
    "compileOnSave": false,
    "compilerOptions": {
      "importHelpers": true,
      "forceConsistentCasingInFileNames": true,
      /* Basic Options */
      "target": "es2015" /* 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": ["dom", "es2015", "es2017"], // "allowJs": true,                       /* Allow javascript files to be compiled. */ // "checkJs": true,                       /* Report errors in .js files. */
      /* Specify library files to be included in the compilation. */
  
      "jsx": "react" /* Specify JSX code generation: 'preserve', 'react-native', or 'react'. */,
      "sourceMap": true /* Generates corresponding '.map' file. */,
      "typeRoots": ["./src/@types", "./node_modules/@types"],

      /* 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. */,
  
      /* 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. */,
  
      /* Module Resolution Options */
      "allowSyntheticDefaultImports": true /* Allow default imports from modules with no default export. This does not affect code emit, just typechecking. */,

      /* this is a fix for issues with Gatsby and GraphQL v15+ */
      "skipLibCheck": true  
    },
    "include": ["./src/**/*", "./custom.d.ts"]
}