tsconfig.json

{
  "compilerOptions": {
    "allowSyntheticDefaultImports": true,
    "esModuleInterop": true,
    "target": "es5",
    "downlevelIteration": true,
    "importHelpers": true,
    "sourceMap": true,
    "module": "esnext",
    "moduleResolution": "node",
    "jsx": "react",
    "resolveJsonModule": true,
    "allowJs": false,
    "checkJs": false,
    "lib": [
      "dom",
      "es2015",
      "es2016",
      "es2017",
      "esnext"
    ],
    "forceConsistentCasingInFileNames": true,
    "experimentalDecorators": true,
    "noImplicitAny": true,
    "noUnusedParameters": true,
    "noImplicitReturns": true,
    "noImplicitThis": true,
    "noUnusedLocals": true,
    "skipLibCheck": true,
    "strictNullChecks": true,
    "suppressImplicitAnyIndexErrors": true,
    "types": [
      "jest",
      "node",
      "webpack-env"
    ],
    "baseUrl": ".",
    "paths": {
      "*": ["custom/*", "src/*"]
    }
  }
}