tsconfig.json

{
  "compilerOptions": {
    "baseUrl": "./",
    "outDir": "./dist/commonjs",
    "target": "ES2018",
    "declaration": true,
    "moduleResolution": "node",
    "esModuleInterop": true,
    "declarationDir": "./dist/typings/",
    "lib": [
      "es2019",
      "dom"
    ],
    "allowSyntheticDefaultImports"    : true,
    "emitDecoratorMetadata"           : true,
    "experimentalDecorators"          : true,
    "forceConsistentCasingInFileNames": true,
    "importHelpers"                   : true,
    "module"                          : "es2015",
    "noImplicitAny"                   : false,
    "noUnusedLocals"                  : false,
    "sourceMap"                       : true,
    "strict"                          : true,
    "strictNullChecks"                : false
  },
  "include": [
    "packages/**/*.ts"
  ],
  "exclude": [
    "packages/**/test/**/*.ts"
  ]
}