tsconfig.json

{
  "compilerOptions": {
    /* Module and Target are calculated by @wessberg/rollup-plugin-ts */
    /* Basic Options */
    "declaration": true /* Generates corresponding '.d.ts' file. */,
    "resolveJsonModule": true,
    "importHelpers": true,

    /* Strict Type-Checking Options */
    "strict": true /* Enable all strict type-checking options. */,

    /* 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 */
    "esModuleInterop": true /* Enables emit interoperability between CommonJS and ES Modules via creation of namespace objects for all imports. Implies 'allowSyntheticDefaultImports'. */
  }
}