tsconfig.json

{
    "compilerOptions": {
        /* Basic Options */
        "target": "es2018" /* 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": [
            "ES2018"
        ] /* Specify library files to be included in the compilation. */,
        "allowJs": false /* Allow javascript files to be compiled. */,
        "forceConsistentCasingInFileNames": true /* Disallow inconsistently-cased references to the same file. */,
        "declaration": true /* Generates corresponding '.d.ts' file. */,
        "declarationMap": true /* Generates corresponding .d.ts.map file */,
        "newLine": "lf" /* Specify end of line character to be emitted. */,
        "stripInternal": true /* Strip declarations marked @internal */,
        "importHelpers": true /* Import emit helpers from tslib */,

        /* 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. */,

        /* Set up paths for all the sub-packages */
        "baseUrl": "./",
        "paths": {
            "@propcheck/core": ["packages/propcheck-core"],
            "@propcheck/core/*": ["packages/propcheck-core/*"]
        }
    }
}