message: Delete dist_demo folder before build
diff: },
  "scripts": {
  "start": "webpack serve --config config/webpack-dev.config.js",
  - "build": "npm run build:types && del dist && webpack",
  + "build": "npm run build:types && del dist && del dist_demo && webpack",
  "type-check": "tsc --noEmit",
  "type-check:watch": "npm run type-check -- --watch",
  "build:types": "del types && tsc --emitDeclarationOnly",
  