tsconfig.json

{
  "compilerOptions": {
    "target": "ES2015",
    // Module settings.
    "allowSyntheticDefaultImports": true,
    "esModuleInterop": true,
    "isolatedModules": true,
    "moduleResolution": "node",
    "resolveJsonModule": true,

    // Strictness and quality settings.
    "alwaysStrict": true,
    "exactOptionalPropertyTypes": false,
    "forceConsistentCasingInFileNames": true,
    "importsNotUsedAsValues": "error",
    "noFallthroughCasesInSwitch": true,
    "noImplicitOverride": true,
    "noImplicitReturns": true,
    "noPropertyAccessFromIndexSignature": true,
    "noUncheckedIndexedAccess": true,
    "noUnusedLocals": true,
    "noUnusedParameters": true,
    "strict": true,

    // Type-checking settings.
    "lib": ["ES2020"],
    "skipDefaultLibCheck": true,
    "skipLibCheck": true,
    "types": ["jest", "node"]
  },
  "include": ["./src/**/*.ts", "tests/**/*.ts"]
}