message: Adding ES2015.Symbol lib to typescript compilation partially fixes
diff: {
  "compilerOptions": {
  "target": "ES5",
  - "lib": ["ES6", "DOM"],
  + "lib": ["ES6", "DOM", "ES2015.Symbol"],
  "module": "commonjs",
  "moduleResolution": "node",
  "downlevelIteration": true,
  